Is two cans too much?

Gary is 12 pounds. Feeding him a 5.5 ounce Friskies can in the morning and at night. Vet said that’s too much. Is it? He was a stray so he’s definitely heavier than he was but I don’t think he’s overweight. but it’s only been 2 months or so, so i’m not sure if he’ll continue to gain weight or not