"Reweld"...does that mean welded a second time? That term has been discussed to death here. We know what you're talking about though.
Guns used to be simply cut to pieces and then enterprising individuals welded the parts together and good to go...so they changed the spec and now parts are removed. Some were torch cut and the ragged edges gave more challenge but not impossible. Most issue would be loss of the metal's properties from extreme heat... Most of the existing runners that have been welded together are good looking or they would have been redone until they were either junk or finished. Don't worry about the ones that have been reassembled. They should be cheaper though.