Colbert and Kimmel were probably both given Paxlovid after their first positive tests. Unfortunately, it is now believed that there is a likelyhood of "rebound" Covid after taking Paxlovid. Essentially, the drug decreases viral load, you feel better, you test negative. But once the medication has left your body, viral load bounces back up, and you start testing positive again. So it's really the same infection.
Also remember that these industries have required frequent testing, so cases will be found more often than in the general population.