As I’m never one to shy away from nonsense arguments... maybe the vast majority would consider 2 years a multi-year deal but it wouldn’t make the person that didn’t wrong. As pointed out, there is more than one definition to the word.
Typically 2 is referenced differently.. such as bi-racial instead of multi-racial in case where it’s only 2 races. A property manager that covers 2 properties is a Dual Property manager and after that its multi-unit manager. All sorts of other terms for 2 such as pair, couple, etc and then multi ends up being used to mean more than 2