We have only one robot. No stunt doubles.
Due to storage space issues our old robots are dismantled/destroyed. We try to keep the stripped down chassis from an old one but we never wind up doing anything with it. After awhile of moving it around and tripping over it it winds up meeting the same fate as the others. We also never have the time to build two robots at the same time. Most of the programming gets done in the 5th or 6th week when there's actually something to work with. It would be nice to have something to work with before that but with our situation it's never worked out.