Can’t merge accounts. These accounts have the same related contact. Remove the redundant account-contact relationships and then try merging again.

If you have "Contacts to Multiple Accounts" feature enabled in Salesforce and tried to merge duplicate contacts or accounts you have probably seen this error message. 

Salesforce requires you to remove the duplicate relationship manually before it can merge the accounts or contacts. 

DataGroomr gets around these Salesforce restrictions by resolving redundant contact account relationships automatically.

Please refer to Merging Duplicate Contacts and Accounts in Salesforce blog for details.