For whatever reason some perfectly fine beans get underroasted. It has been known to happen. The simple question is, do you bin them straight off or do you try to rescue them by roasting them a second time.
It's not a recommendation.
It's not "reheating." It's finishing the roast. It works, i.e. you can bring the pre-roasted beans to first and on to second crack.
The beans that I've tried it on, Brazilian and Kenyan have turned out quite well. I used them in blends and the results were fine. Some beans may not take to it at all well. YMMV (Yes My Mind Vacillates).
If you don't want to bother, don't have the time, toss them. But it can't hurt to try. You can bin them afterwards if you don't like them.
Most meat sauces taste better after they have had time to harmonise.