I was preferring Emmerson (spelt the original way) but I really want to keep that for if we have a boy next time.
Go with whatever name you two like regardless of other opinions, but it might sound a bit odd if you have two children with such similar names. So I'd say just use the one you love the most this time around. Personally, I'd stick with the original spelling of Emmerson to avoid having to spell out a long name every time someone is writing it down.