My parents dog (whose name was Sophie) used to answer to 'Mochyn' (Welsh for pig) and 'Piglet' because she made noises akin to a pig's snuffling and, being a spaniel, was usually covered in mud...
My dog (Seren) answers to - in no particular order - 'The Dog', 'Dog', 'Soppy' (because he is), 'Dip'/'Dippy', 'Bro' (my DS' name for him), 'Sweets', 'Pudding', 'Splodge', 'Muttley' (because he laughs just like the cartoon dog), 'Mummy's Baby' and - very rarely - 'Serendipity' (but that's only when he's in real trouble, because that's actually his name... and it's usually when he's doing something he knows he ought not to be doing, but the boundary pushing is just a little too tempting...).
He also goes off to find my DS when I ask him where "his baby" is. They grew up together, as DS was 18 months old when he came to join our tribe, and is brilliant with him. I'm dreading the day he has to finally leave us, tbh, because I know it's going to break his beloved "baby"'s heart more than it will mine. My parents are "Biscuit Nanny" and "Granddad" - and he differentiates between them both, and yes, he knows that I'm "Mum". DS' Dad, meanwhile, he ignores totally... and whilst he seems fond of her, my DD (who was 9when he came to us) is someone whom he also tends to ignore command wise. He can also differentiate between which of our cats is safe to go near/cuddle up next to, and which he has to avoid (he's bullied, slightly, by one of them) even though, at a quick glance, they look alike (two tuxedos, two tabbies). And he has to have a piece of (junk mail) post every day that he runs around showing everyone. It's got to the point now where one of our postmen will actually hand him a bit of junk mail, rather than pass it across to me with the rest of the post... but then, my dog's very loved!