Copy issue instead of move - leave old issue in place, generate new, create link automatically

Basically, we need to be able to promote issues from a public tracker to a project tracker if they resolve to a bug. The move capability allows us to shove them into the bug list, but we would like to leave the original issue in the public tracker and indicate with a comment or status field that it has been promoted to a bug in the non-public system. So, rather than Move, how about Copy, and for both, how about creating a comment automatically to indicate that the issue came from elsewhere to the new tracker?