This is, in my opinion, another case of developer illogic creating conflicts in the code without need.
As there is no weight unit measurement class in MS 2.2 or CRE Loaded, there can be ONLY one weight unit used in the cart without setting yourself or your client up for some very interesting and obscure shipping problems later on.
So - there should, ideally, be only ONE place for the weight units to be defined anywhere in the cart.
That said, it's also less labor, and wasted time is wasted money.
David