That can easily be avoided if the Party leader set Duty Completion under the purpose tab before queueing up on the duty list. If someone already have cleared it up for the week, it's going to show an error message and the party won't be able to proceed.

It's written on the Duty list on a bright, neon yellow color. The problem is that people seem to not even try to pay attention or read those things. The explanation on the duty list is pretty on point and easy to understand.

The issue is: If the leader is the one with the weekly clear, and is advertising 2 chests, then he is the one that should be punished.

Quite frankly it should be possible to check the completion of party members prior to even entering the party if it's set up for savage anyways. That would prevent a lot of headaches.