The limit isn't always 100%. The way I've always heard is 100% is the original design limit, and the other amount is what it can actually do. Say they upsize a turbine, it may bump the max limit from 100% to 105%.

Somewhat of an example: the original Space Shuttle engines were rated at 100% design thrust. Through a series of upgrades, they eventually gained some more power, allowing 104% of original design thrust continuous. This is the 'maximum power' that was used during climb.

Citation III's max N1 is 101.5%, the Dash-8 Q200 can go to I think 115% (we were limited to 105%) torque, etc. etc.