From aa3ee64526343b7eadbf36f4c3cce97d6b7297be Mon Sep 17 00:00:00 2001
From: Cj <161484149+CJ-SPT@users.noreply.github.com>
Date: Tue, 30 Sep 2025 12:06:14 -0400
Subject: [PATCH] Prevent `key has already been added` exception when checking
 for duplicate mods and building `modPackageData`

---
 SPTarkov.Server/Modding/ModValidator.cs | 15 ++++++++-------
 Testing/TestMod/TestMod.csproj          |  8 ++++++--
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/SPTarkov.Server/Modding/ModValidator.cs b/SPTarkov.Server/Modding/ModValidator.cs
index 81631708..8b08a066 100644
--- a/SPTarkov.Server/Modding/ModValidator.cs
+++ b/SPTarkov.Server/Modding/ModValidator.cs
@@ -23,11 +23,11 @@ public class ModValidator(ISptLogger<ModValidator> logger, ServerLocalisationSer
         // Validate and remove broken mods from mod list
         var validMods = GetValidMods(mods).ToList(); // ToList now so we can .Sort later
 
+        CheckForDuplicateMods(validMods);
+
         // Key to guid for easy comparision later
         var modPackageData = validMods.ToDictionary(m => m.ModMetadata.ModGuid, m => m.ModMetadata);
 
-        CheckForDuplicateMods(modPackageData);
-
         // Used to check all errors before stopping the load execution
         var errorsFound = false;
 
@@ -82,19 +82,20 @@ public class ModValidator(ISptLogger<ModValidator> logger, ServerLocalisationSer
     /// <summary>
     ///     Check for duplicate mods loaded, show error if any
     /// </summary>
-    /// <param name="modPackageData">Dictionary of mod package.json data</param>
-    protected void CheckForDuplicateMods(Dictionary<string, AbstractModMetadata> modPackageData)
+    /// <param name="validMods">List of validated mods to check for duplicates</param>
+    protected void CheckForDuplicateMods(List<SptMod> validMods)
     {
         var groupedMods = new Dictionary<string, List<AbstractModMetadata>>();
 
-        foreach (var mod in modPackageData.Values)
+        foreach (var mod in validMods.Select(mod => mod.ModMetadata).ToArray())
         {
-            groupedMods.Add(mod.ModGuid, [.. groupedMods.GetValueOrDefault(mod.ModGuid) ?? [], mod]);
+            groupedMods[mod.ModGuid] = [.. groupedMods.GetValueOrDefault(mod.ModGuid) ?? [], mod];
 
-            // if there's more than one entry for a given mod it means there's at least 2 mods with the same author and name trying to load.
+            // if there's more than one entry for a given mod it means there's at least 2 mods with the same GUID trying to load.
             if (groupedMods[mod.ModGuid].Count > 1)
             {
                 SkippedMods.Add(mod.ModGuid);
+                validMods.RemoveAll(modInner => modInner.ModMetadata.ModGuid == mod.ModGuid);
             }
         }
 
diff --git a/Testing/TestMod/TestMod.csproj b/Testing/TestMod/TestMod.csproj
index cb614f39..459a5d64 100644
--- a/Testing/TestMod/TestMod.csproj
+++ b/Testing/TestMod/TestMod.csproj
@@ -2,6 +2,7 @@
   <Import Project="..\..\Build.props" />
   <PropertyGroup>
     <ImplicitUsings>enable</ImplicitUsings>
+    <AssemblyName>TestMod2</AssemblyName>
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\Libraries\SPTarkov.Common\SPTarkov.Common.csproj" />
@@ -16,10 +17,13 @@
       <Resources Include="$(ProjectDir)Resources\**\*.*" />
     </ItemGroup>
     <!-- Copies the output dll -->
-    <Copy SourceFiles="@(OutputDLL);" DestinationFolder="$(SolutionDir)\SPTarkov.Server\bin\$(Configuration)\net9.0\user\mods\TestMod" />
+    <Copy
+      SourceFiles="@(OutputDLL);"
+      DestinationFolder="$(SolutionDir)\SPTarkov.Server\bin\$(Configuration)\net9.0\user\mods\$(TargetName)"
+    />
     <Copy
       SourceFiles="@(Resources);"
-      DestinationFolder="$(SolutionDir)\SPTarkov.Server\bin\$(Configuration)\net9.0\user\mods\TestMod\Resources\%(RecursiveDir)"
+      DestinationFolder="$(SolutionDir)\SPTarkov.Server\bin\$(Configuration)\net9.0\user\mods\$(TargetName)\Resources\%(RecursiveDir)"
     />
   </Target>
 </Project>