Promoting to a Source Code Twice

Is there a way to promote two lists at two different times to the same source code? 

On one of our mailing projects, we currently promote a group of constituents to an appeal/generate source codes and then pull the same segments/criteria a few weeks later in order to add any additional sales.  This second list pull generates a set of new source codes for the same duplicate segments/criteria.  In some of these appeals there are a high number of source codes.  It would be very helpful for reporting purposes if they weren't duplicated by the two list pulls and the second list pull could be promoted to the existing source codes.

Thanks in advance for the insight.   

Charles Buchanan

Manager, Direct Marketing and List Management

92nd Street Y