I saw this boat on lake Elsinore, Ca. about 5 months ago when they were testing it. I spoke to Fred Inman Imco Owner) and he said it's a little less expensive than having 2 motors.
This setup is mostly used on small 21' ski boats with big power (1000+HP) to make it keep the boat level because the torque kept it hard to keep the boat level. The power distributed through 2 drives makes the boat run better.