Constrain Supply Plan generates duplicated Planned Orders

Hello,

We have an item with the following configuration in the PIM:

When we run the supply plan with refresh, the plan has proposed two Planned Orders for the same Item in consecutive weeks. From the item configuration, we understand that planned orders should be proposed on a monthly basis, so we do not know why the system has not merged the two planned orders.

We have also run plan without refresh and the plan has proposed new planned orders. Is this possible? Isn't it supposed to generate no new proposals as we have not chosen the refresh option? Also for the same date we already had a signed order. What makes it re-propose the same quantity for the same date?