Yes, you essentially have to take 1 extra HQ, and 2 Extra troops to unlock the second force org.
A better way to look at it is that each primary detachment (and you can have 2 at 2000 pts) nees 1 HQ and 2 troops, minimum. Allied's need 1 HQ 1 Troop.
So if you wanted both Primary, and both allied detachments, you'd need 2 primary HQs, 4 Primary troops, 2 Allied HQs, and 2 Allied troops, minimum.