Yeah, I've never in my life ordered anything other than a large. You gotta get deep dish, and the whole wheat crust is delicious, it's actually better than the standard white. So it's a thick, substantial pizza pie.
But let's do some math. Conan's website says the small is 10" and the large is 14". So total area of the small is 98.5 in^2, and the total area of the large is 138 in^2. So half the small is 49 in^2. Back in my high school and college days I could just about eat a large by myself. But these days I'm older and wiser and I'm also not a great big fat person, so usually 2 out of 8 slices on a large, is enough for me. That's 34.5 in^2 which is less than half of the small, so the small would be sufficient for 2 people. If you wanted to do 3 slices, you'd get 51.8 in^2 out of a large, which is slightly more than the 49 in^2 that represents half of a small.
In conclusion, the small is probably okay for two, as long as you are not great big fat people.
But seriously, why? Just order the large and make sure you have enough for some leftovers. It's great the next day.