During the import wizard for COBRAS you get the chance to decide if you want to create a new DL (you'll have to change it's name to be unique) or just import members from that backed up DL into the existing DL on the target system.
The import wizard is pretty extensive - you are required to resolve all conflicts prior to import - COBRAS isn't just going to pull the trigger and let the chips fall where they may - it should help you resolve all that stuff up front for all objects.