I've read that people add the amount of bounty that people have into the pot by diving the bounty by the the initial bounty and multiplying that by the starting stack. So for example in a 20$ mtt we have 9$ bounty in the beginning and the starting stack is lets say 3k. So if at some point someone goes all in with a 18$ bounty on him we add 6k into the pot.

But since we only get 9$ out of the 18 and the other 9$ goes to our bounty so we will get them only if we win the tournament, shouldnt we add only 1.5k for every 9$ in the bounty?