They do split the pay. However if you get a driver that's not pulling his or her weight as far as amount of miles driven in a timely manner it can be frustrating because that person is costing both drivers. So the temptation is to not bother the other driver when you've driven your legally allowable hours. Simply switch to their logbook and keep going. This isn't legal but it's done. Married teams do it occasionally but for two strangers thrown into a team truck to fo this is unusual.
What you are saying don't make any sense in regard to the OPs question and problem. Why would a co driver jump your clock like this? Why would they want to? This was one of my first thoughts when I first read the question.
What are you doing that you have time on your log that's available to be used? Maybe you spend too much time back in the bunk? Perhaps it's time to actually do some work.
Sometimes someone posting a question don't provide all the information. It is extremely difficult to answer a question thoroughly with less then all the info.
The only reasonable explanation might be that he thinks the OP isn't putting in enough miles during his shift or the OP might be hard as heck to wake up. An unreasonable explanation is he might not be sleepy and figures why not drive while I have the mojo going.
Guess common sense ain't so common anymore. If I ever caught someone intentionally driving on my logs, there'd be hell to pay.
I understood your point and I agree. What I was trying to say was if both drivers are paid for the total miles the truck gets, why would a co driver jump the other drivers clock. This is what makes no sense to me. What is there to be gained?
Obviously, if one driver is a slacker and only produces 9 hours a day and the other driver produces 11 hour a day, the driver producing 13 hours a day will get the truck back up to full 22 hours a day productivity.