You might have both a slight flood on one carb and clogged idle jets or screws. Or possibly no flood but an inlet leak. This would better explain it. When carbs flood, they usually stall if choked. If they don't flood but idle circuit clogged as I said, they require a bit richer mixture to run, like you get if you choke.
Write down how many turns to seat idle screws( they will be different), remove and don't mix them up, spray out with carb cleaner, replace exactly as many turns. Don't lose the springs, washers, O rings. They go back together: screw, flat washer, spring, flat washer, then O-ring. Tighten fuel lines. If still gas smell, remove bowls check needles, floats, seating, float height. You can see roughly if needles seating and sealing by blowing on inlet line and gently raising floats with fingers. Should stop air flow a bit before top of floats are parallel with the carb base. Should also seat at about same height--use a bubble level held evenly on both floats to see.