Two checkboxes appearing when reassigning transaction

Has anyone faced the same issue? Two options/records for one user appear when we attempt to reassign a transaction through Transaction Console - this occurs when it reaches the second /third approver. We cannot approver until one of the checkboxes are ticked.

Any ideas on what the numbers in the brackets represent? We have checked and this user does not have two assignment records, and the numbers don't match the person number or transaction number.