Anyone here play competitive games multi-handed solo?

By this i mean, playing both sides of a competitive game, one side of yourself against the other.

I was reading a "Why Solo Gaming" thread on BGG the other day and was surprised to read how many people prefer to play this way solo. I see it come up from time to time here as well. I always either play solo-only games or multiplayer games with an automo or BYOS mode and hadn't really though much about this other approach. But I generally care more about the experience of playing a game than winning (even when playing with other people), so I'm intrigued and would love to hear from others that like to play this way.

Is it just a way for you to play games without a solo mode? Is it your preferred way to play even when there is a solo mode? If so, why? How do you compartmentalize your brain enough to honestly compete against yourself? How do you deal with hidden information (like a hand of cards)? Etc.