oh my god i found the source

source/funkin/game/PlayState.hx

@@ -627,19 +627,20 @@ class PlayState extends MusicBeatState
 				name = "Unknown";
 		}
 
+		for(k=>e in noteTypesArray)
+			if (e == name) return k;
+		
+		noteTypesArray.push(name);
+
 		// loads script
 		var scriptPath = Paths.script('data/notes/${name}');
-		if (Assets.exists(scriptPath)) {
+		if (Assets.exists(scriptPath) && !scripts.contains(scriptPath)) {
 			var script = Script.create(scriptPath);
 			if (!(script is DummyScript)) {
 				scripts.add(script);
 				script.load();
 			}
 		}
-
-		for(k=>e in noteTypesArray)
-			if (e == name) return k;
-		noteTypesArray.push(name);
 		return noteTypesArray.length-1;
 	}
 	function sortByShit(Obj1:Note, Obj2:Note):Int

source/funkin/scripting/ScriptPack.hx

@@ -15,6 +15,12 @@ class ScriptPack extends Script {
         }
     }
 
+    public function contains(path:String) {
+        for(e in scripts)
+            if (e.path == path)
+                return true;
+        return false;
+    }
     public function new(name:String) {
         additionalDefaultVariables["importScript"] = importScript;
         super(name);