Yup, that's my conclusion as well.
You have made me feel a lot less crazy.
I've just never run into something like this before. I've run into a few situations where there was an unknown controlled group issue, but never something like this where the TPA (a big, well-known name) administered both plans.
I just kept looking through the files and going, no, no, no, no, wtf??? Ha.
I feel for my client.