Anyone ever seen one like this?

I picked this catchers mitt up last week.I has a really interesting backside it almost looks like a basemans mitt from the back,it has some rivets.I have never come across a catchers mitt with this style of back.Anyone ever seen this before?There are no makers marks or writing visible.It seems like it is a well made mitt.I took some pictures of it .Any help on this one would be appreciated.
thanks
dave s



thanks
dave s