Do you add a version number to PBIs that have multiple iterations

Sometimes your team will work on a PBI, finish it in the Sprint, and receive feedback about changes or extensions that weren't originally asked for in the Acceptance Criteria. 

Bad Example: Unlimited new tasks get added to that PBI so it takes multiple Sprints to finish

Good Example: A new PBI is added to the backlog called "<original PBI name> v2". If this then happens again, a v3 is created, and so on

This has the added bonus of allowing the Product Owner to see, at a glance, how many rounds of feedback he's given to the team on each PBI.