Double commuting would be having to commute to an airline job and to a guard unit. For example, you live in Florida, but commute to Newark, NJ to fly for Continental and also fly for the Texas Air National Guard. There are quite a few people who do this, but they tend to be more senior at the ANG and only fly in for drills and one or two flights per month. As a new guy, this is going to be very hard to do because you'll have a lot more training requirements.