This will occur when the Federal Tax ID Number listed on each of your merchant accounts is identical. Page 2 of your Form 1099-K will provide a monthly breakdown for each account reported under the listed Federal Tax ID Number.
What if I need each of these accounts to report separately moving forward?
You may send in a copy of your signed W-9 form AND an EIN documentation to 1099corrections@shift4.com and we will have this updated for the current tax year.