The toys in the 2 pack aren't a standalone release (as) yet.
It goes like this:
2 pack
Deluxe Earth Mode Optimus prime with Battle Damage
Deluxe Cybertron Mode Megatron with Battle Damage
Standalone
Deluxe Cybertron Mode Optimus Prime
Voyager Cybertron Mode Megatron
Voyager Earth Mode Optimus Prime

The 2 deluxe OP's are basically the same mould though, different mainly in chest piece and arms - and the axe as you pointed out.