I'm going out on a limb here and will take a guess that the number that's posted is probably the correct number of the butterfly that was recovered ~ presumably they read that directly off the tag. Then I believe they look up who the tagger was (or who they sold the tag to, anyway) either from the returned tagging reports database or from the sales records for the tags. Probably someone just looked it up incorrectly or it was a typo, or you have a name very similar to another tagger's and the search returned his recoveries? In any case, there's a reporting form on the database where you can send in corrections; you could just tell them the tag number and that it's not one of yours and they can probably figure out whose it really was.
Certified Monarch Waystation #12
near Philadelphia, Pennsylvania