Hello,
Yes, it is possible, but there are two different things that can cause the desktops to look the same.
First, check OneDrive. If Desktop backup is enabled, both computers may be using the same Desktop folder stored in OneDrive. On each computer, click the OneDrive cloud icon > Settings > Sync and backup > Manage backup and check whether Desktop is being backed up. If you want completely separate desktop files on each PC, Desktop backup should not be enabled for both devices.
Also check:
Settings > Accounts > Windows backup
Windows can sync some preferences when the same Microsoft account is used on multiple devices. You can turn off the appropriate Remember my preferences options if you want each PC to keep its own personalization.
If two different people are sharing the same Windows sign-in, though, I would recommend creating a separate Windows user account for each person instead. That gives each person their own Desktop, Documents, settings, browser profile, and app preferences.