So I bought new rear drums today - found something strange (to me). I decided to go with quality made in USA drums. I brought the drums home and opened them up and found just one has a balancing weight tack-welded to the surface. The part numbers are the same. I've never encountered this before and was wondering if this is unusual? Should the weighted one go one side or the other? Should I return it? Thanks for the input.
You are OK. In mass production parts some have to be balanced. That is all that you are seeing. My rears have several "weights" attached and they have a lot of race laps on them with no problems.
This is one of those cases that if you do not have the weights added you need to worry.