Hi Dane,
I'm Rodrigo and I will help you.
This is happening because you have the OneDrive backup enabled for the Desktop folder. In order to stop it syncing on both devices, you need to disable it on at least one of them.
to do it, right click the OenDrive icon on the taskbar > Settings > Backup tab > Manage Backup > On "Desktop" select Stop backup.
This will stop OneDrive from syncing the files of this device's Desktop. But all the files on OneDrive will still be there.