1 files changed, 19 insertions, 1 deletions
diff --git a/src/SMAPI/Program.cs b/src/SMAPI/Program.cs
index aecf5b30..e9084b2d 100644
--- a/src/SMAPI/Program.cs
+++ b/src/SMAPI/Program.cs
@@ -765,7 +765,7 @@ namespace StardewModdingAPI
                                 IContentHelper packContentHelper = new ContentHelper(contentManager, packDirPath, packManifest.UniqueID, packManifest.Name, packMonitor);
                                 return new ContentPack(packDirPath, packManifest, packContentHelper, this.JsonHelper);
                             }
-                            
+
                             modHelper = new ModHelper(manifest.UniqueID, metadata.DirectoryPath, jsonHelper, contentHelper, commandHelper, modRegistryHelper, reflectionHelper, translationHelper, contentPacks, CreateTransitionalContentPack, this.DeprecationManager);
                         }
 
@@ -993,6 +993,24 @@ namespace StardewModdingAPI
                     }
                 }
 
+                // validate translations
+                foreach (string locale in translations.Keys)
+                {
+                    HashSet<string> keys = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
+                    HashSet<string> duplicateKeys = new HashSet<string>(StringComparer.InvariantCultureIgnoreCase);
+                    foreach (string key in translations[locale].Keys.ToArray())
+                    {
+                        if (!keys.Add(key))
+                        {
+                            duplicateKeys.Add(key);
+                            translations[locale].Remove(key);
+                        }
+                    }
+
+                    if (duplicateKeys.Any())
+                        metadata.LogAsMod($"Mod's i18n/{locale}.json has duplicate translation keys: [{string.Join(", ", duplicateKeys)}]. Keys are case-insensitive.", LogLevel.Warn);
+                }
+
                 // update translation
                 TranslationHelper translationHelper = (TranslationHelper)metadata.Mod.Helper.Translation;
                 translationHelper.SetTranslations(translations);