Mortifier / Penitient Engine Melee Weapon Question

[Montford]

Just want to make certain I am doing this correctly:

 

If I have either a Mortifier or a Penitent Engine equipped with 1 Buzz Blade and 1 Penitent Flail then I may make that models 4 attacks using either weapon profile: the choice is mine. The only thing I will be giving up is the additional attack if I would have had both melee weapons be the same.

[Atrus]

Correct. Sacrificing extra attack for versatility. Or the other way, take 2 of either and sacrifice versatility for extra attack.