Prefab texture changes oddly

So basically I have 2 prefabs with a blue diffuse texture. I then copy these prefabs because I need version with yellow texture. I press ctrl+d while having them selected in the project window. However then when I change the texture of any of these prefabs it changes for all of them as if they are linked. Any ideas? Thanks.

Ooh it was so obvious :confused: I was using the same material in all prefabs so when I changed the texture I changed the material as well.