Depending on the state it was titled in it could have been re-titled as either "salvage" or "reconstruction" which basically means it was made from a pile of parts of different vehicles with titles and purchase receipts for all the major parts, so Dept of Motor Vehicles has covered their ***** before issuing a new title under either a new vin tag or one of the vin tags of the major contributing carcases.
In this case it would be a "B" line title, not an "A" line title , which is a good title, but it means "something happened" .
In any case, if you bought it, a trip to the state offices is in order, with the seller in hand, to "splain" everything and make sure it's "legit".