Why did some Mercedes come with 1 Fuel pump & some models two?

[chasinthesun]

Ive been working thru fueling issues on two Mercedes ,both are the model 190e with the cosworth motor ,the 1985 model was fitted with just one pump ,while the 87 has duel pumps.I completed the 85 with a replacement tank installed followed by a list of new fuel related parts with good results on startup .I have know started working on the 87 , it seems to have the same issues such as the rusty tank but faired better than the 85 with a better maintinence shedule looking at some of the fuel related components.Since I want to give the 87 cossie motor a stir after its long sit of 10 yrs or more I was wondering if I could pull the fuel filter and pump setup off my 85 to make a run at it.A look at the wiring for the duel 87 fuel setup has double the wiring ,would it be alright just to wire both pos. and both neg. leads to the one leg on the one pump setup ?