TrainerRoad doesn't have an official solution for allowing two riders to do a workout on the same computer at the same time. We currently do not support any kind of a "companion" application.
That being said, two riders _can_ ride at the same time so long as each rider has their own laptop, desktop, or mobile device.
Keep in mind that it's TrainerRoad's policy that each account only be linked to a single person, and each account owner may download the application to as many devices as s/he would like.
If you have any other questions about multiple users riding with TrainerRoad, please email our Support Team for clarification at firstname.lastname@example.org.