Generating PO from Multiple line Requisition not closing requisition properly

Hi all

I have an issue as below, please may you assist. 

When Generating a Purchase Order from a Multiple Line Requisition, the system seems to not close the last line correctly.  The last line on the Requisition is called up twice for generation.  If the user just generates the PO, it adds a quantity of 1 to the Original quantity entered on the Requisition.  For example if the last line was for a quantity of 10, the system adds a quantity of 1 and creates the Purchase order with a quantity of 11 on the last line.

Your assistance will be much appreciated.