I don't think it's weird at all that you can tell one cat's voice from another's. I usually could, when I had two cats in the house. Sylvie had a pretty, soft voice and she trilled, like a human who rolls their r's. Freak was louder, didn't trill, and had that "ow" tone that often comes with Siamese heritage. If I heard, "Myrrrrrhhhhuh?" I knew it was Sylvie, whereas "MRAAOOW!" was Freak.