HI Sanrda,
The process here its wrong nothing to do with the time constraint here even its 1 or 2 or 3 if you are clicking on the Change icon then current record will be appearing where if you are changing the record obviously the record will be overwritten.
So here what you have do is that ask the HR Admin to use the copy or create option so that the previous records gets delimited and the new record gets created so that history is there in the system.
Regards,
Mithun K