MM is only the entitlement to download the photos. I'm not sure what rules it follows. If it is part of a package (like over the summer we got a free MM with a stay) then you won't get the MM until you check into your second resort and therefore I don't think it would include all of your pictures. If it isn't attached to the package in that way and is just something that you bought in addition, I don't see why it wouldn't cover the pictures that are take prior to the second stay. You could always call PP to verify that it is there and will be active upon arrival and not as of your check in for the second resort if you aren't sure.