Maintain the condition records for all the required condition types in FV11. JMX1, JEX1, JHX1 100% and for JMOP, JEC1, JSEP 0% and choose that tax code in PO. Now perform the same cycle in Dev or Qas server and let us know your findings.
In general, for Trader procurement scenario PO value will be Inclusive of Excise duty and you change the Excise Base value and duties during MIGO/J1IEX as per the Vendor invoice and tick MRP indicator in Excise header and while MIRO you must to change the amount manually and Post Invoice document.
Please Search the forum with search term trader / dealer purchase and you get the desired results.