Yep Rick..it's been that way for a LONG time.
At one time eBay was going to do away with half.com but decided not to.
I just sold in February via half.com. I put that book up two years ago and to be honest, I'd forgotten about the listing as you the seller don't get any updates. So when I sold the book and got a notice..I went WHOA!
I'm lucky I still had the book! <smile>
You have the same ID with half.com and Yes, the accounts are merged together.
Hope the info helps Rick,