Reading this carefully, what I get from the initial transaction is that the couple originally wanted to check three bags.....they ended up checking two bags @ $20.00 each/ total $40.00.

The agent was not saying that the third bag was $50, she was apparently saying that if they checked in a third bag the charges would be as follows - Passenger #1 - one bag = $20.00.
Psgr #2 - two bags = $20/1st bag and $30/2nd bag = $50.

As it turns out they checked in a total of two bags so that was $20 each psgr = total $40/correct. Also there is no way to override the EZCkin to print bags tags without showing that money was collected and cash cannot be collected at the EZCkin. The agent would have had to been interacting with a cashier on the counter. Lobby agents do not have a cash (locked) drawer. Some stations maintain cash drawers for each agent (behind the counter) and some have 1 or 2 agents with a cash drawer but never if one is working as a lobby agent.