The id record assigned to a duplicated record is not sequential. Usually there is a jump of several Id number.
The same occurs even after editing a record: 1. create a new record, the Id is 540. 2. Then edit another record, save and close 3. Create a new record. The Id assigned is 542. There is a jump of one Id.
I think that the problem is due to multiple call that the system do to the Next Number service.
If you create different new record, one by one, the assignment of the Id is sequential.