If you play monopoly with house rules that make it more similar to a real mix of sovereign economies, surely the latter. (Source: I have played with such house rules. Yes, it gets more interesting than vanilla monopoly. Yes, that's how inflation happens in those games. One bank has never, so far, suddenly decided to give people money they don't need (that sounds like financial suicide). External events, however, have caused changes in demand for one bank currency which forces that bank to lend more money.)