I vote that this is a mistake on the listing by Festool. The original listing does include both the large countersink and the imperial set which includes the large countersink. It does not really make sense that Festool would have included two of that countersink in the collection. Since the picture includes the centering bit and the set listing does not, I think it is just a case of oversight on the part of Festool. If your go through some of their catalogs carefully, you can find inch dimensions that are incorrect. Mistakes happen.
If Festool wants to pass out extra countersinks, I will take one. However, I do not think that Sean should try to make up for Festool's error. I think Festool should just acknowledge the error and let that be the end of it. These are already reasonable deals, so nobody is really getting hurt by not getting an extra bit of kit.