Going to a new area, after updating BoP, gave Corrupted Sands in the middle of the ocean. So I took a look at the ID's to see if something had been changed somehow. I found these two biomes sharing the same ID number:
I:"Corrupted Sands ID"=105
I:"Kelp Forest ID"=105

Looking through the other numbers it turns out that Tropics and Coral Reef also share the same number, 104.

Also, I had a request, please please don't change the id number on biomes, if it is avoidable. It can be such a mess to figure out when updating the mod, and still playing the same map. (I don't know if you guys are already trying to avoid it)

That's because we haven't readded all of the biomes yet, so when new ones are readded and you download that new version, there will be biome ID conflicts. Just delete the config file for them and create a new world.

I thought minecraft did away with numerical IDs, and just assigned them dynamicaly, so there wouldn't be conflicts anymore. But maybe that doesn't apply to biomes?