Pair point. On that part I was wrong. I agree with you, I was only entitled to an extra piece (which ironically would be 23kgs, higher than the 20kgs for the weight concept). So the computer was potentially correct but what I don't know is what the senior did. He/she either overrode based on what I was telling the lounge agent (an extra 20kgs) or he/she too (like me in this situation) doesn't know the correct additional allowance. Or, perhaps one final thought is the person downstairs found the lounge agent lacking in logic and agrees with us here who believe there's no reason why can't take a cherry from both baskets.
In addition to the issue I'm having (finding a non-human way to do what I want, correctly), it would appear that my recent experience here also confirms that somewhere in Qantas staff are being told that the cherries come from basket and one basket only.