If you install CRM server more than once on same machine, you will end up with more AD security groups than necessary. They will not do any harm, but every decent admin tries to keep his AD tidy.
From AD management tools it’s not very obvious which groups are latest and in use, but simple SQL query will solve the mystery. Just run the following query in any active organizations database. It will give you the names of two groups, but you can deduce others you will need.
SELECT SqlAccessGroupName, ReportingGroupName FROM Organization
Just to be on the safe side… Don’t delete groups just yet. Move them in some other OU, test the server and delete them after you confirm everything is still working.