Is it possible to gauge two piercings together?

I don't think so. However, if you're not concerned about your ear shrinking back down at any point (honestly if you're going to stretch, you shouldn't because even smaller sizes can be permanent for some people) your piercer may be able to scapel the tissue between the two piercings. Now it'll take a while to heal, but if all goes correctly the end result will look fine, and you could even start with a size significantly larger than you'd be able to by simply stretching.