So, I heard back from GC-Minis about my double shipment. They thanked me for letting them know. They said they would beat the shipping trolls responsible for the error. They told me to keep the books and they hoped I could trade them for something I can use.
I thought that they were good people. This means that I can hard-use the sets I have and still have a nice set for the bookcase. Or maybe even give the Space Wolves rules to my son.