Is this on a server?
Some servers run an addon that combines dropped entities together for performance reasons. So if you drop 30 torches on the ground near each other, they'll combine into a single stack of 30 torches. I suspect this is what's happening with your armor (not sure why, since combining armor is a recipe. But that's my best guess)
Sorry, yes this is on a multiplayer server. I understand the grouping of drops into stacks but I didn't think this worked to combine broken armor into fully repaired armor. It also happens with enchanted armor. I get only broken pieces if the chest is empty but if I cleanup after I get fully repaired pieces of enchanted and unenchanted gold, leather and chain armor.
 
				
		 
 
		 I miss the mod a lot, but I also don't miss it, if that makes any sense.  haha   Sometimes doing things the hard way is more fun (and more aggravating).  AE2 is still way out of the question, not using vanilla recipes.
   I miss the mod a lot, but I also don't miss it, if that makes any sense.  haha   Sometimes doing things the hard way is more fun (and more aggravating).  AE2 is still way out of the question, not using vanilla recipes.