This has been done before and race directors (no names mentioned:)) look at it, damhik.
Simple senario: A friend runs with a friend's chip to get him qualified for Boston or just a fast time. The problem is that all of the mats give the exact time within 1/100th of a second throughout the course. Then at the finish line they are close, but not exact. They review the photos and bingo, there is one guy at each mat at that time, not 2 runners with different chips. But at the finish, there is 2. Too easy but also too obvious to smart race directors who don't like cheaters.
This cheater is smart enough to know that so he doesn't have someone do that, so IF confronted, he just claims the mat didn't recognize his chip because most times there is a photograph, not a constant video recording. When there has been, bam baby, he has no explanation and is DQ'ed.
Yes, he could have an accomplice, you may be right, but I doubt it because he wouldn't want to risk loose lips. If you research a course before hand you can really get the lay of the land. Check out the Crim course that Einstein spoke of, super easy to cheat on. The more runners the easier it is. Look from about 6-8 miles. This guy is not smart so please stop overthinking this. He's just a cheater while the rest of us actually run the race. Ciao!