Two Headed Cats Aren't Called Siamese Cats?

Two-faced cat earns Guinness world record: MyFoxBOSTON.com

WORCESTER (FOX 25 / MyFoxBoston.com) - A Worcester cat has two names, one body, two faces, and now a spot in the Guinness World Records. Frank and Louie was born with two faces, a condition called Janus. Cats born this way generally live a day or two, but the Worcester Telegram & Gazette says Frank and Louie are celebrating their 12th birthday. That is a world record.

Yes! Another chance to ad-lib an El Pres Post (Quotations hypothetical, of course):

GET IT OFF ME! I literally spit out my coffee and I wasn't even drinking coffee. This has to be some kinda sign of the apocalypse, or some shit. Cats born this way normally live a day or two, huh? No shit hunny. Cats with one head are enough of a terror, demon cats spawning second heads just can't be tolerated. I in no way condone violence against animals, but this thing isn't your average animal, and I'm fairly certain cat owners are off'ing two headed cats after a day of dealing with their devious ways. It's just too much cat to handle, even the crazy cat ladies from TLC couldn't put up with this shit. It's diabolical.

In all seriousness though, how is the name of the condition for a two headed cat called Janus? Not Siamese? Really guys? Am I wrong for thinking that we call Siamese twins, Siamese twins because of the cats? I'm so confused right now, like if ever there was a layup case of something being Siames-ish I thought this would be it. Now I'm going to have to go spend an hour or so on wikipedia figuring this shit out. Might as well call out of work today.

Sharing an eyeball must absolutely suck