Change blah.Add(key, value) to blah[key] = value;

The former throws an exception when adding a duplicate key, while the latter doesn't.

Have you tried the most recent iTweenPath from my blog? If so can you send me a project that I can take a look at?

Mike 3 has it right in general terms above.

The actual change to iTweenPath.cs that I made is:

    void OnEnable(){
    if(!paths.ContainsKey(pathName)){
       //paths.Add(pathName.ToLower(), this);
       paths[pathName.ToLower()] = this; // updated from http://answers.unity3d.com/questions/49137
    }
}

As you can see I commented out the original line and added the replacement line: paths[pathName.ToLower()] = this;

This fix works my situation when I was instantiating the same prefab from a spawn point multiple times. Hope this makes it easier for all.

Oz.

Oh my god thanks guys so much for the easy fix.... Much appreciated...

I added these lines before line 17 and I no longer get that error, Im moving the path nodes around in my script, and the changes were not taking effect when I loaded the scene, then left, and loaded the scene again. The 2 lines below are a quick fix, pixelplacement maybe you want to look into this?

    if(paths.ContainsKey(pathName.ToLower()))
        paths.Clear();

        paths.Add(pathName.ToLower(), this);