I keep most of my horses in a small barn I built in my survival world. I have about 10 of them and they are different designs. I walked pasted them on the recent update (1.8) and they all had the same skin as the horse I most recently rode. The skin was black sooty (the black color with white spots/dots).

I expected to see the different horses with different skins I have (it's how I tell them apart).

What I saw was 10 or so horses all with the same skin (impossible to tell apart).