When importing updated existing action records, ImportOmatic doesn't have the functionality to match on the solicitor that exists on the action record—because of this, ImportOmatic interprets the incoming solicitor as a duplicate record, which causes an error. The only fixes for this are to remove the solicitor from the records that have errors or to un-map the action solicitor field completely. Neither of these are reasonable options, especially if you are trying to automate the import process.