If two ID types are setup that contain a dimension (or dimensions) that have the exact same name and length, then this will force the system to twin the accounts. If you do not want to twin the accounts:

1. Select General Ledger, Maintenance, ID Types
2. Select the ID type from the drop-down
3. Click the Account Structure tab
4. Change the name of the dimension that has the exact same name and length of the dimension in the other ID Types
5. Click OK