The sleep proxy protocol allows multiple sleep proxies on the network. In fact, most recent Macs also run their own built-in sleep proxy (dependent on something in the wifi chipset, I believe). I'm pretty sure this is a Yosemite bug.
My temp fix is a keyboard maestro action on wake that resets my computer name.
It isn't a 10.10 bug, this problem has been around since Apple introduced Wake On Wireless in 10.6.