[qup]

Doubt it, the bill reader checks all the bills before dispensing, so it would be bypassed for monopoly money.

Maybe they used $1s or something.

[kotaKat]

Nah, they get 'test money' to load into the dispensers, and it's something banks will also buy for things like ATM demonstrators.

https://shop.dieboldnixdorf.com/atm-demonstration-currency/p...

(We haven't really had "ATM demonstrations" in a long time specifically, but there was a bit of time in the early adoption era to get a fake card into a customer's hand and let them play with a demonstration machine in your lobby or in an office to get to see how convenient it was to get the play money out. See also the tabletop demonstrator Triton built, the ATM Jr - https://triton.com/about-triton/innovative-history/)