Are cats really clever???

Funny thing happened tonight while i was a having a few beers !
a cat jumps onto my living room window ledge and starts to tap the window with his paw,immediately my dog (yorkshire terrier)goes berserk and makes a beeline for the cat whilst barking crazy,eventually the dog calms down and it turns into a staring match between the cat and the dog through the window much to our amusement
strange thing is do i went into the kitchen to get another beer and in my kitchen theres another cat who obviously came through the dog flap installed eating the dogs food and the second it seen me was gone back out like a shot
question is do you think the two cats set up the dog by distracting it whilst the other eats the dogs food and then swap places or did i have one or two more beers than i should had????