@Covalt, Jonathan G, Thanks for posting in Q&A.
From your description, I know the previous enrolled device will disappear from Intune after we enroll another. Based on my researching, if the devices share the same serial number. the issue can occur. Please check if the two devices are with the same serial number.
To check the serial number, you can run the following command in command prompt:
wmic bios get serialnumber
Please check the above information and if there's any update, feel free to let us know.
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