Does it have the Ballard "tulip"?  (The round profile next to the receiver.)  If so, ain't likely to be anything else.

That's a very common thing to find with Ballards. Often people either shot the barrel out form so many rounds, or wanted a different caliber, so they found a donor and put another Ballard barrel on. I've probably got 6-7 Ballards with barrels the serial numbers don't match. Some even have Win. or Stevens barrels on them, and a couple are even marked by Stevens as rebarreled by them. I have a Pacific #5 in .45-70 that has a mismatched serial number. Still a Pacific barrel as it has all the thimbles and cross screw for the forearm. If I hadn't checked I would have never known it was a donor barrel.
I don't think the barrel numbers being mismatched hurts very much if they put the proper Ballard barrel on to match the model you have.