Thanks for reporting this! There was a bug where, for the last week or so, whenever a new player challenge was created, it (accidentally) copied the score and user ID off the sniper challenge as if that person (who made the sniper challenge) had gotten that score in the challenge that was just created.
There were 219 challenges that were inadvertently awarded to the wrong player because of this bug. I have erased the scores from those challenges and reopened them -- so for the next 24 hours, until 3 PM tomorrow, there are a TON of challenges open. By 3 PM tomorrow it will be back to normal. Anyone who was credited with defeating a challenge that way (including Merlin) has had that credit rescinded, though for the next 24 hours anyone can play those challenges for real and possibly win them now that the bad scores have been erased. (and the bug has been fixed so this won't happen again)