Overwriting others?

hello

I tested it shortly with birds/cats and unfortunately see that there ware available (not earlier generated) avatars overwritten. That would my users not like 🙂
My Avatars come from Gravatar and from Plugin “WP Social” by registering.

For now I go back to Identicon (Generated) because it is not so invasive, seems that only those manually uploaded stay untouched.

The page I need help with: [log in to see the link]