Very rarely, someone will upload a new avatar that has a blueprint ID that overwrites another that was uploaded by another user. It happens a few ways:
1) The old avatar is gone, and it is overwritten for both users.
2) The old avatar is now on the New Avatar Uploader's list, and the avatar that was uploaded is now in the Old Avatar Uploader's list.
Is it possible that we're getting Blueprint ID collisions? It seems strange that it happens so often for a randomly generated string.