I'm cleaning up any duplicates that have been added by list import and, for the time being, would like to start with only those leads I've imported.
Is there a way to edit my Smart List's "View" so I can see who owned the import?
No, it's not something that is logged. I understand Marketo is working actively on the audit trail idea (Audit Trail (Vote on this Idea, not it's dupes)) but I do not know if this info will be made available, furthermore in a lead field so that you could display it in a view.
This is more something that you may want to ask users to provide in a custom field in the future, but anyhow, it will still remain subject to user's discipline.