Do pets really know their own names?

I firmly believe that a pet does know its given name after awhile. I have had dogs all of my life, and they have all known to come when their name is called. We have at times had more then one and once again they seem to know which one your talking to when you say their name. Funny, thing is the dogs we currently have will sometimes act like they don't know their name in order to get away with mischief, but we know better, and tell them as much.