A lot of people work on a project. Handlers are assembled, reassembled, tested, retested, etc... Sometimes mistakes are made and it isn't clear who made them which leads to some testy situations between coworkers. The person initially assembling may not be the person who disassembles or reassembles and people don't always know who exactly did what-when. It comes up, it's annoying, but it's not a big deal. As long as you do your best and are consistent, this issue will be minimized.