If you do 6/1 2/off then a 2-1 on the next roll would leave an odd number of men and therefore be a wasted roll. That would be an unnecessary gift to your opponent.
If there had been one more man on the ace point (or one less) at the start of the 5-2 then it would make no difference which you did. The 2-1 would reduce your bearoff requirement by one roll whether one man came off or two.
although it seems like a waste of pips it might win me a move which is important
are there also positions in which its better to move only 1 piece into you home because it covers an empty spot (and leaving 1 outside your home) than moving 2 pieces into your home (and leaving that spot empty ?)
for example you all your pieces in your home except 2 .. those 2 are both on 8 while 2 is empty .. you 4+2 .. would you move 1 piece to 2 and leave the other at 8 .. or would you move 8/6 and 8/4 leaving 2 empty ?