diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,19 @@
 # Changelog
 
-## [0.6.0.4] - 2024-10-24
+## [0.7.0.1] - 2024-10-27
+
+### Changed
+
+* Fixed a bug in which `allOrNothing` (and `subSettings`) could malfunction
+  when using a common library setting multiple times.
+
+## [0.7.0.0] - 2024-10-27
+
+### Added
+
+* The `allOrNothing` error now shows which settings were defined.
+
+## [0.6.0.4] - 2024-10-26
 
 ### Added
 
diff --git a/opt-env-conf.cabal b/opt-env-conf.cabal
--- a/opt-env-conf.cabal
+++ b/opt-env-conf.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           opt-env-conf
-version:        0.6.0.3
+version:        0.7.0.1
 synopsis:       Settings parsing for Haskell: command-line arguments, environment variables, and configuration values.
 homepage:       https://github.com/NorfairKing/opt-env-conf#readme
 bug-reports:    https://github.com/NorfairKing/opt-env-conf/issues
diff --git a/src/OptEnvConf/Doc.hs b/src/OptEnvConf/Doc.hs
--- a/src/OptEnvConf/Doc.hs
+++ b/src/OptEnvConf/Doc.hs
@@ -14,11 +14,14 @@
     renderManPage,
     renderReferenceDocumentation,
     parserOptDocs,
+    docsToOptDocs,
     renderLongOptDocs,
     renderShortOptDocs,
     parserEnvDocs,
+    docsToEnvDocs,
     renderEnvDocs,
     parserConfDocs,
+    docsToConfDocs,
     renderConfDocs,
 
     -- * Internal
diff --git a/src/OptEnvConf/Error.hs b/src/OptEnvConf/Error.hs
--- a/src/OptEnvConf/Error.hs
+++ b/src/OptEnvConf/Error.hs
@@ -6,10 +6,13 @@
 
 import Data.List.NonEmpty (NonEmpty (..))
 import qualified Data.List.NonEmpty as NE
+import Data.Map (Map)
+import qualified Data.Map as M
 import qualified Data.Text as T
 import GHC.Stack (SrcLoc)
 import OptEnvConf.Doc
 import OptEnvConf.Output
+import OptEnvConf.Setting
 import Text.Colour
 
 data ParseError = ParseError
@@ -34,7 +37,7 @@
   | ParseErrorConfigRead !(Maybe ConfDoc) !String
   | ParseErrorMissingCommand ![CommandDoc ()]
   | ParseErrorUnrecognisedCommand !String ![CommandDoc ()]
-  | ParseErrorAllOrNothing
+  | ParseErrorAllOrNothing !(Map SettingHash SrcLoc)
   | ParseErrorUnrecognised !(NonEmpty String)
   deriving (Show)
 
@@ -59,7 +62,7 @@
   ParseErrorConfigRead _ _ -> False
   ParseErrorMissingCommand cs -> not $ null cs
   ParseErrorUnrecognisedCommand _ _ -> False
-  ParseErrorAllOrNothing -> False
+  ParseErrorAllOrNothing _ -> False
   ParseErrorUnrecognised _ -> False
 
 eraseErrorSrcLocs :: (Functor f) => f ParseError -> f ParseError
@@ -122,9 +125,11 @@
             [fore blue "available commands:"]
           ]
             ++ availableCommandsLines cs
-        ParseErrorAllOrNothing ->
-          [ ["You are seeing this error because at least one, but not all, of the settings in an allOrNothing (or subSettings) parser have been defined."]
+        ParseErrorAllOrNothing locs ->
+          [ ["You are seeing this error because at least one, but not all, of the settings in an allOrNothing (or subSettings) parser have been defined."],
+            ["The following settings have been parsed:"]
           ]
+            ++ map (pure . srcLocChunk) (M.elems locs)
         ParseErrorUnrecognised leftovers ->
           ["Unrecognised args: " : unwordsChunks (map (pure . chunk . T.pack) (NE.toList leftovers))],
       maybe [] (pure . ("see " :) . pure . srcLocChunk) parseErrorSrcLoc
diff --git a/src/OptEnvConf/Parser.hs b/src/OptEnvConf/Parser.hs
--- a/src/OptEnvConf/Parser.hs
+++ b/src/OptEnvConf/Parser.hs
@@ -71,9 +71,7 @@
     commandTraverseSetting,
 
     -- ** All or nothing implementation
-    parserSettingsSet,
-    SrcLocHash (..),
-    hashSrcLoc,
+    parserSettingsMap,
 
     -- ** Re-exports
     Functor (..),
@@ -90,17 +88,16 @@
 import Data.Aeson as JSON
 import qualified Data.Aeson.KeyMap as KM
 import Data.Functor.Identity
-import Data.Hashable
 import Data.List.NonEmpty (NonEmpty (..))
 import qualified Data.List.NonEmpty as NE
+import Data.Map (Map)
+import qualified Data.Map as M
 import Data.Maybe
-import Data.Set (Set)
-import qualified Data.Set as S
 import Data.String
 import Data.Text (Text)
 import qualified Data.Text as T
 import qualified Data.Text.IO as T
-import GHC.Stack (HasCallStack, SrcLoc, callStack, getCallStack, prettySrcLoc, withFrozenCallStack)
+import GHC.Stack (HasCallStack, SrcLoc, callStack, getCallStack, withFrozenCallStack)
 import OptEnvConf.Args (Dashed (..), prefixDashed)
 import OptEnvConf.Casing
 import OptEnvConf.Reader
@@ -1138,28 +1135,21 @@
   (\p -> c {commandParser = p})
     <$> parserTraverseSetting func (commandParser c)
 
-parserSettingsSet :: Parser a -> Set SrcLocHash
-parserSettingsSet = go
+parserSettingsMap :: Parser a -> Map SettingHash SrcLoc
+parserSettingsMap = go
   where
-    go :: Parser a -> Set SrcLocHash
+    go :: Parser a -> Map SettingHash SrcLoc
     go = \case
-      ParserPure _ -> S.empty
-      ParserAp p1 p2 -> S.union (go p1) (go p2)
-      ParserSelect p1 p2 -> S.union (go p1) (go p2)
-      ParserEmpty _ -> S.empty
-      ParserAlt p1 p2 -> S.union (go p1) (go p2)
+      ParserPure _ -> M.empty
+      ParserAp p1 p2 -> M.union (go p1) (go p2)
+      ParserSelect p1 p2 -> M.union (go p1) (go p2)
+      ParserEmpty _ -> M.empty
+      ParserAlt p1 p2 -> M.union (go p1) (go p2)
       ParserMany p -> go p
       ParserSome p -> go p
       ParserAllOrNothing _ p -> go p -- TODO is this right?
       ParserCheck _ _ _ p -> go p
-      ParserCommands _ _ cs -> S.unions $ map (go . commandParser) cs
-      ParserWithConfig _ p1 p2 -> S.union (go p1) (go p2)
+      ParserCommands _ _ cs -> M.unions $ map (go . commandParser) cs
+      ParserWithConfig _ p1 p2 -> M.union (go p1) (go p2)
       -- The nothing part shouldn't happen but I don't know when it doesn't
-      ParserSetting mLoc _ -> maybe S.empty (S.singleton . hashSrcLoc) mLoc
-
--- An 'Ord'-able SrcLoc
-newtype SrcLocHash = SrcLocHash Int
-  deriving (Eq, Ord)
-
-hashSrcLoc :: SrcLoc -> SrcLocHash
-hashSrcLoc = SrcLocHash . hash . prettySrcLoc
+      ParserSetting mLoc s -> maybe M.empty (M.singleton (hashSetting s)) mLoc
diff --git a/src/OptEnvConf/Run.hs b/src/OptEnvConf/Run.hs
--- a/src/OptEnvConf/Run.hs
+++ b/src/OptEnvConf/Run.hs
@@ -26,9 +26,9 @@
 import Data.List (find)
 import Data.List.NonEmpty (NonEmpty (..), (<|))
 import qualified Data.List.NonEmpty as NE
+import Data.Map (Map)
+import qualified Data.Map as M
 import Data.Maybe
-import Data.Set (Set)
-import qualified Data.Set as S
 import qualified Data.Text as T
 import Data.Traversable
 import Data.Version
@@ -325,7 +325,7 @@
   let ppState =
         PPState
           { ppStateArgs = args,
-            ppStateParsedSettings = S.empty
+            ppStateParsedSettings = M.empty
           }
   let ppEnv =
         PPEnv
@@ -421,19 +421,19 @@
                 then ppErrors' errs
                 else do
                   -- Settings available below
-                  let settingsSet = parserSettingsSet p'
+                  let settingsMap = parserSettingsMap p'
                   -- Settings that have been parsed
-                  parsedSet <- gets ppStateParsedSettings
+                  parsedMap <- gets ppStateParsedSettings
                   -- Settings that have been parsed below
-                  let parsedSettingsSet = settingsSet `S.intersection` parsedSet
+                  let parsedSettingsMap = settingsMap `M.intersection` parsedMap
                   -- If any settings have been parsed below, and parsing still failed
                   -- (this is the case because we're in the failure branch)
                   -- with only forgivable errors
                   -- (this is the case because we're in the branch where that's been checked)
                   -- then this should be an unforgivable error.
-                  if not (null parsedSettingsSet)
-                    then ppErrors' $ errs <> (ParseError mLoc ParseErrorAllOrNothing :| [])
-                    else ppErrors' errs
+                  if null parsedSettingsMap
+                    then ppErrors' errs
+                    else ppErrors' $ errs <> (ParseError mLoc (ParseErrorAllOrNothing parsedSettingsMap) :| [])
       ParserCheck mLoc forgivable f p' -> do
         debug [syntaxChunk "Parser with check", ": ", mSrcLocChunk mLoc]
         ppIndent $ do
@@ -490,8 +490,9 @@
                   ( \loc -> modify' $ \s ->
                       s
                         { ppStateParsedSettings =
-                            S.insert
-                              (hashSrcLoc loc)
+                            M.insert
+                              (hashSetting set)
+                              loc
                               (ppStateParsedSettings s)
                         }
                   )
@@ -725,7 +726,7 @@
   let ppState =
         PPState
           { ppStateArgs = args,
-            ppStateParsedSettings = S.empty
+            ppStateParsedSettings = M.empty
           }
   let ppEnv =
         PPEnv
@@ -866,7 +867,7 @@
 
 data PPState = PPState
   { ppStateArgs :: !Args,
-    ppStateParsedSettings :: !(Set SrcLocHash)
+    ppStateParsedSettings :: !(Map SettingHash SrcLoc)
   }
 
 data PPEnv = PPEnv
diff --git a/src/OptEnvConf/Setting.hs b/src/OptEnvConf/Setting.hs
--- a/src/OptEnvConf/Setting.hs
+++ b/src/OptEnvConf/Setting.hs
@@ -34,6 +34,8 @@
 
     -- * Internal
     showSettingABit,
+    SettingHash (..),
+    hashSetting,
     completeBuilder,
     mapMaybeBuilder,
     emptySetting,
@@ -45,10 +47,11 @@
 where
 
 import Autodocodec
+import Data.Hashable
 import Data.List.NonEmpty (NonEmpty (..), (<|))
 import qualified Data.List.NonEmpty as NE
 import Data.Maybe
-import OptEnvConf.Args (Dashed (..))
+import OptEnvConf.Args (Dashed (..), renderDashed)
 import OptEnvConf.Casing
 import OptEnvConf.Reader
 import Text.Show
@@ -88,6 +91,26 @@
     settingMetavar :: !(Maybe Metavar),
     settingHelp :: !(Maybe String)
   }
+
+-- An 'Ord'-able Setting without giving 'Setting' an 'Eq' instance
+newtype SettingHash = SettingHash Int
+  deriving (Show, Eq, Ord)
+
+-- We hash only the parts of the setting that have anything to do with how the
+-- setting is parsed, not the parts that are for documentation.
+hashSetting :: Setting a -> SettingHash
+hashSetting Setting {..} =
+  SettingHash
+    ( 42
+        `hashWithSalt` map renderDashed settingDasheds
+        `hashWithSalt` settingTryArgument
+        `hashWithSalt` length settingReaders
+        `hashWithSalt` isJust settingSwitchValue
+        `hashWithSalt` settingTryOption
+        `hashWithSalt` settingEnvVars
+        `hashWithSalt` (NE.map configValSettingPath <$> settingConfigVals)
+        `hashWithSalt` (snd <$> settingDefaultValue)
+    )
 
 data ConfigValSetting a = forall void.
   ConfigValSetting