I ran a Bell component overhaul shop for a short time. We were often sent components for recertification from third party parts suppliers. We had to be extremely careful with drivetrain components as the Bell sudden stoppage inspection states that if you find any damage as you do the inspection, many components require scrapping, not overhaul.
We had a case where a one 212 fly bar arrived for recertification, the book stated that any damage, both were scrap. I thought it unusual that we asked to only recertify one, not two, this involve a full visual and MPI inspection. We asked were the other bar was, no comment, just send that bar back uncertified.
No idea how many of these types of parts are floating around awaiting recertification.