Based on customer feedback we have finished and published an update for our Interspire Email Marketer Suppression Management product. This addon makes it easier to import, export, search & delete suppressed contacts and much more related to managing suppressed contacts.
We thought it necessary to take a new and fresh run at developing that feature in an actual addon that is not vulnerable to IEM updates and is compatible with all version 6.0+ and with the most popular existing addons on the market today.
If you need to export contacts from multiple contact lists the default interface of Interspire allows for that. Via the Export Contacts menu you can select as many lists as you want. There are a few things that are not very intuitive.
Your current best option is to export the two (or more) contact lists and attempt to merge them into a single excel file. Sort by one of the columns and search for duplicates. It is tedious for certain but it also is a huge time waster.