We have a data import error where a large number of individuals have two partners, instead of just the one they should have. This causes errors with another system we use that is linked to civicrm. I need to delete the duplicate relationships. Thanks for your help!
One possibility is to export the Relationship civireport (under Reports - Contact Reports) and then use the power of Excel to analyze it, e.g. pivot on contact_a and relationship-a-b and have it sort by count descending, then anything with 2 or more is a duplicate.