Well the idea of the challenge is not just for "programming" a game together, but to build and develop the game together. As many, who have been involved in the indie game dev scene long enough, know there is much more than one role to play when making a game, though indies often wear plenty, if not all, hats when working on their projects.

The idea of the challenge would not be to share all hats or just the programming side alone, but to divide up or split certain tasks amoung the 2+ of you. There is also other aspects of working in small team that can be considered a skill too. It's not just to complete more things for a project, but to have an easier time working off each other's strengths to make a stronger result of your work.