Hi Jaisree,
Could you please explain your issue in detail. Some screenshots will help a lot.
Do you expect your PO number should followed by the previous PO ? There could be some other process running in parallel which may also create orders, please have a check
PO which are created in APO holds the Temp number, when it transfered to ECC (CIF) a real PO number will be created and same will be sent to APO (CIF) again which replaces the Temp PO number.
Regards
Vinoth