Might just be the same person with two or more stands. I' d leave the landowner out of it as he proablly doesn' t want the trouble and might kick both of you off.

Well here' s what happen to me as the guy that placed a stand up near someone else' s once. Not on purpose mind you,haha. I was setting stands on my Uncles land, not ever thinking he' d given someone else permission to hunt it. A few days later some guy called me up being very nice, and telling me who he was. Turned out to be a old friend to my uncle, and I' d accidentally placed my stand about 50yds from his. I offered to pull mine, but he said it wasn' t necessary. We worked it out so I hunted mine on the wknd' s, and he hunted his during the week being retired and having more time. It was a decent spot, and both of us saw deer, but passed on small bucks. As it turned out him and I became good friends. We had alot of similar likes, and ethics. I enjoyed that fall sharing stories of that area, we chatted quite often.
So I guess my point is I' d try to call the guy before season starts, and have a nice chat. He might turn out to be a decent guy, and if he isn' t you' ll know heads up to stay clear of him, and not waste your hunting woods time worrying about him!