Planned order avail/require date is same but having start date different in each planned order

Hi All,

Planned order created by SNP run (CTM) always has different start date  and end date same in APO.

The same planned order when we check in ECC its different but same in ECC.

Example:

Planned Order           Start Date              End Date

In APO                    11/06/2016             20/07/2013

In APO                    12/06/2016             20/07/2013

In APO                    13/06/2016             20/07/2013

In APO                    10/06/2016             20/07/2013

In APO                    09/06/2016             20/07/2013

In RRP3/Product view all the orders have same avail/requirement date.

In PDS, activity duration (fixed) is 13 day for setup and handle.

How the activity duration (fixed) figure populates in PDS i believe it from work center ?

Please provide the info what could be the reason for SNP planned order have not the same  start date in APO.

Let me know if required any information to undersatnd the facts.

Regards,

Deepika