The income from a 1099-K would be reported as Additional Income on Schedule 1. You will be properly reporting your gambling income from both the W-2g and the 1099-K on Schedule 1 Line 8b. The total income from Schedule Part 1 Line 10 flows to your Form 1040 Line 8.
You will have entered your total income received and that income should be the same as what the IRS is expecting to see on your tax return.
If the IRS was to ever question you on the income reported on the 1099-K your response is that it was properly reported as gambling income on Schedule 1 and that additional income was properly reported on your Form 1040.
