I don't really see the problem with two slightly different spellings, as long as they're understandable, and I don't see why they aren't. It's just a couple of letters here and there.

But actually all American scientists, as far as I know, do use the metric system. And it's being taught in science classes. I wish suck it up and switch because the "English system" is too complicated. I think we will eventually switch because the younger generations are more accepting to change. It's obviously a problem with politicians worried about not getting the votes of people who are afraid to wake up and standardize with the rest of the world.