You can have both an active Entra and active Workspace at once.

If you want to sync groups, users, and services from multiple Entra accounts or Workspace accounts, you can sync one, deactivate that integration, and sync the other account afterward.

However, you can only have one Entra or Workspace integration activated each time, so you will not be notified of any changes in your AD unless that account is activated in Substly.