I didn't use it. I have it in my library, available to use, but I never used it.
@Mask3D_WOLF, are you asking me to pull out my Resource Pack(s) and try it again?
EDIT: Correction, I did have it enabled. It was hidden below the Default Pack. I'll give it another go, now that it's officially disabled.
Updated with the crash report
I'm working on getting that Crash Report. I don't know if/how this glitch triggers, so I'm stuck playing online and hoping it happens again so I can send that your way.
As soon as it happens, though, I'll send it your way.
Updated with a photo of the glitch. The skin is different, entirely dependant on who's in the game (it's always someone else; never myself). I couldn't get a proper screenshot, since it overlays the menus and couldn't get it to stay when I exit fullscreen. I dunno if it's only doing this in fullscreen or not, but I do know it disappears when I exit fullscreen. So no proper screenshot.
I've played in a number of servers, such as Mineplex [us.mineplex.com], Hypixel [mc.hypixel.net] & Wynncraft [play.wynncraft.com]. This happens pretty much every time I play online.
Updated with a new crash log, without my Resource Packs. Glitch still happened.
Oddly enough, however, I noticed that the skin was changing this time. Still overlayed, but it switched between three different skins this time.