I'm sorry to bump an old thread, I came here for something else (first time poster here).
I've never had a cat that didn't know their own name and the idea that a cat wouldn't is strange to me. It probably depends on how a cat is raised, but in a family with kids, giving the cat a name as a kitten, the cat picks up their name pretty quickly cause it's the word they hear most often. I agree that cats are more into listening for tones and they may respond to children's voices better than adults due to higher pitch, but I've had over 10 cats in my life and every one knew there name.
One cat, Vivian, she would respond to any similar sound like Lidian was just as good. (She was my brother's cat, later mine, and we never did experiments but probably other names like Didian, Vidian, anything like that might have work, and/or, she might have figured out the game and ignored the similar sounds after that - cats are smart that way).
Another cat I got already given and familiar with her name, "Precious", she used to come when she was called. She was raised in a one cat household when they had to get rid of her at 1 year and I had her sister so I took her in. (bad idea, they had no idea they were sisters after 1 year and there was some battles for territory). But 2 things happened. Precious figured out that Shadow (her sister/my other cat) didn't come when called so after about 2 weeks, precious stopped coming when I called her, what's more, Shadow figured out then when I called Precious, she wants to see what was going on, so she'd come, but shadow never came when I called her, she'd just look at me. Both cats seemed to not only know their own names but the other cat's name.
I've also had cats, when feeding them, would meow when their name was called (when there was no food on the counter, that performance wasn't repeated), but 2 cats in the same room, each one would meow after their name, they wouldn't both meow.
I think, raised with a name as a kitten, virtually all cats know their name and the idea that one wouldn't is a strange concept to me, but it might depend a lot on the situation the cat was raised in and how often he/she hears their name. I don't know about taking in a stray cat as an adult.
I do agree with some of the posts above, cats also respond to tones. That's accurate too, but there's name recognition as well and my cats recognizing and responding differently to the other cats name, said in the same tone, seems like strong evidence of that to me that they know both their name and the other cat's name and I've had 2 sets of cats that responded that way.
Now, does the cat know that as her name? Or hear her name as some kind of command? No way to know. My cat Shadow was really smart and she one time, started chewing on a wire (I know, that sounds dumb right), but I said her name in a different tone and she totally got it and she never chewed on a wire again at least for several years, as she got older she stopped listening to my instructions but I got several years of her leaving all wires alone. She could figure things out like that. I taught her never to scratch a person in the face in a similar same way, by tapping her on the side of the head, not hard, but stern and saying no, and she never scratched a person in the face again after that. Kittens are kind of programmed to learn things and figure things out, even if they don't learn command behaviors the way dog's do. Learning their name is something even the dumbest kitten should be able to do - imho.