I equipped a horse with a saddle and golden horse armour.
When I wanted to try to unequip it and to place an iron armour, the golden armour appeared to be still there - I couldn't see the iron armour on the horse although it was equipped with it.
Restarting the world didn't fix it, I had to totally logout from the Launcher and shut it down, and restart the Launcher - then the "ghosting" armour was gone.
I've made Screenshots of it (attached).
Edit: Here is a short <1min private-listed video where you can see it (no audio):
I couldn't re-do that problem with the ghosting armour.
All I can remember is that I tried to apply the iron armor directly onto the gold armour (as you can do it with your own playerchar - switching armourpieces while you have them in your hand, just clicking the according armour slot).
I have found more bugs that I will report after this one.