My inference is that an agent may make an exception through ignorance. But as I said, I’d have my cc ready to pay the $25/bag. I am not aware of any way around this unless flying in F or with very high AS status. I don’t think the $25 is discounted by paying in advance.
OP - US law requires that your e-ticket receipt show the cost of checking a first and a second bag. What does your e-ticket receipt show? That is what the check-in agent will see on screen when you check in. No need to shove papers at the agent or smile.