You will want to enter both forms into your tax return just as they have been reported to you. You enter the 1099-K and Form W-2G in Less Common Income following the steps @LeonardS outlined above.
After you have entered both forms in their entirety, you can enter a negative value in the Miscellaneous Income section of Less Common Income for the amount reported on your W-2G. That way it is only being taxed once. It will be reported once on your W-2G, once on your 1099-K, and then one of those will be subtracted from your taxable income by entering the value as a negative in Less Common Income.
@Tee99
