The Duplicate Constituent Management Tool, added in version 7.93, allows you to mark two records as "Not a Duplicate", so that they will not show up in future duplicate runs. However, there is no way to see which records have been marked liked this, or to reverse it if added in error.
The "Duplicate Exclusion Table Manager" is a free utility in Omatic Software's DBA Toolkit app that does exactly this. It's available for free in AppOmatic:
http://www.omaticsoftware.com/Solutions/AppOmatic.aspx