I am not a tax professional.
You said the 2 payouts were issued by 2 different payers. This means that you should have received 2 Form 1099-R s - one from each payer. If so, enter each 1099-R separately.
If you only received one 1099-R, you may be missing the second one, or you may have been paid by the same company. Your employer or plan representative should be able to help you determine this.
Finally, if you are in fact being paid by 2 separate companies and receive 2 1099-R s, you likely now have 2 "retirement plans" (401k s) and would need to take an annual RMD from each plan. (This is different for IRA's.) For details see: https://www.irs.gov/retirement-plans/retirement-plans-faqs-regarding-required-minimum-distributions#...
