I have an upcoming LH F flight booked as an M&M award ticket, booked some weeks ago. I currently hold SEN status.

I also have some Lifemiles points that I would like to "get rid of" before they expire.

The F cabin is currently half full (F4). If LH releases two more F award spaces to partners (<72 hrs before flight or so), would there be any dupe check & cancellation risk if I book two more F tickets on the same flight (same pax names) using Lifemiles points, and then immediately call M&M to cancel my original M&M booking?
I do not dare to do it the other way around because Lifemiles bookings can be hit or miss.