...who lives two streets away (we know the owner) and likes hanging out in our neighbours’ front garden. Looks so completely like our cat in terms of size and colouring that we sometimes assume it IS our cat until he smugly appears from upstairs, so the neighbours probably don’t realise there’s two of them.
It would obviously BU to stick a sign in the kitchen window saying “that’s not our cat, ours is upstairs”. Especially as our cat sometimes goes and sits on their windowsill and peers into their kitchen as if it’s his!