I personally had one claimed by another hunter once, and it was ok by me. I had shot a buck, not a huge buck but a ten point medium size buck and began tracking down a ditch in the snow. Plenty of blood, he wasn't going far, when a hunter I knew to be near the road at the end of that ditch fired a shot. I figured fine, he got him and I'm done tracking, no big deal. There were much bigger bucks to try for anyway and only one tag to use. So, a few hours later I talked to this guy at the road and he wanted to show off his buck, having no idea that I was the guy who chased it to him. I congratulated him on his buck and mentioned this fact. He got all weird and defensive and had to be leaving now and denied that it was already hit when he shot it, although I know he only fired one shot and there were two holes plainly visible. And of coarse he heard me fire before the deer came to him. Anyway I tried to calm him down and assure him it was his deer and I didn't want it and he quickly left.
I wondered later if he fired to stop me from looking any further, and to create an oportunity to claim that deer.
Now, I've always hunted with the notion that whoever finishes the deer keeps the deer. I mean if it has travelled over say, 100 yds and is still on it's legs and moving, it's fair game for anyone. This rule has always been the way it's done for me and folks I hunt with. So to me it was perfectly ok for this guy to take that buck. Plus it was not an especially good buck, so no need to fight about it. But if that deer had died and I had come upon someone else butchering it, it would have been mine and a fight to the death may have taken place.
Another time I heard a shot close where nobody should be and went to investigate. A fellow had killed a huge buck with 7 points on one side. Unfortunately the other side had been broken off completely and the guy was sick about it. He was actually sneaking away when I caught up to him and informed him he was tresspassing. I then called my dad on the phone and told him to drive around and get the number off this guys truck because he wouldn't ID himself. He knew then that he was caught and started complaining about how it wasn't fair that he should have to use his expensive out of state tag on that buck. I informed him that it wasn't fair that I should have to spend my hunting time on my land dealing with poachers either but that there was no way he was not getting the game warden called on him unless I saw a tagged deer. He tagged the deer in front of me and I left the property and drove to where his truck and my father were sitting on the road. Called the game warden anyway, and explained the situation. No charges for tresspassing, but the warden should check to see that the deer was checked in before the deadline that night, I learned later that it was. So that is another problem. Abandoning a deer because it wasn't what you thought it was when you fired.