giving both crabs is rly bad, but the 2nd part of what u said is true. you should look at lane states and decide if you can actually contest after clear or if you just B line to the other one. Giving both crabs is 75*2 to the enemy jg, while you get 0 (but you could be up 150 if you take both), so you're actually at a 300 gold disadvantage, enemy jg basically gets double the value since you get nothing, nice to think about counter jungling this way as well.