@N E , From your description, it seems the device is already enrolled. Could you go to Intune portal and see if the devices is under All devices.
Meanwhile, please check if the device is register to Autopilot.
If yes, remove them and try again. In addition, please also check if the device is under AAD. If yes, try to remove it either.
If there's any update, feel free to let us know.
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