It seems that there are three likely scenarios, listed in order of likelihood:
1. The James' and two other teams are the F3 and twins and dark green are decoying
2. The Chippendales, twins and dark green team are the F3 and the Chips are a ways ahead of the other two
3. The Chips and one of those teams and one other unknown team are the F3 and the other of the spotted teams is decoying and happens to be near the other who is actually racing
Evidence for them being decoys:
1. Wearing backpacks
2. Flip flops
3. No camera or sound seen
4. The convenient twitter account made to post pictures of only these two teams
5. The fact that they are far behind the Chippendales
Evidence for them not being decoys:
1. The helicopter near them
2. It was getting late to be decoying
Am I missing anything?