Skin problem

So I've been playing MINECRAFT for a pretty long time and I don't know if it's a bug or what it is but me and my brother and my nephew have been having problems with the custom skins.

So I put my Fox skin on and my brother had a ender like skin and my nephew was being Steve and right when I turned to my Fox skin not a minute later I had his skin and he had my skin.

 

So I got tired of it and decided to report it it's really bugging me cause it's copying the skin that I have on and he's my skin. 

 

Please fix it.