without more context, my advice is to declare blankrupcy. Just throw away one of the systems, preferably both, and start over. Entering the bugs you are currently working on in a new system.
If you get problem report from the field you could look it up in the old systems to see if it is known, then add it to the new system. The point is the old systems have bugs you Ain't Gonna Fix Unless Something Changes (AGFUSC), and the SC woudl be "another complaint from the field", so re-enter it.
Ron Jeffries has an interesting article on this called petition the king that he uses to extend to even include new features!
http://xprogramming.com/articles/petitiontheking/