This feature helps you save time by creating a copy of your league with the click of a button.
If you'd like to practice simulations with different draft orders, for instance, the duplicate league option is helpful. It recreates your league by preserving settings such as long Keeper lists while allowing you to quickly make any draft order adjustment.
To use the feature, simply click the 'Duplicate' button next to your league on the 'My Leagues' page. From there, you'll be able to make any adjustments to the existing league settings you'd like.