MRP run shows incorrect procurement proposal quantity

Hi Experts,

I have a situation where the MRP Run for a material(MD02) shows incorrect procurement proposal quantity. The Lot size selected is "4 week Lot Size", expectation is that the MRP run should consolidate the 4 weeks of forecast quantity and create a purchase requisition, after rounding based on the "Rounding Value". what is happening is for the 1st purch requisition it shows 4 week quantity and for the 2nd & 3rd requisitions it shows 5 weks and 1 week quantity as shown in the screen shot,please advise!