Is there an existing method to roll with advantage or disadvantage from a character sheet other than having to simply roll twice? 

It would be nice to see a button added for adv/dis 

Right-click. Then select advantage or disadvantage as required. Works on any d20 roll on sheet.

If you right-click other rolls like damage, you get options like "Critical" to roll critical damage.

Right click works on a laptop, but if you're using a phone or tablet, it's a long press.

Thanks for the information!