@Felix, Thanks for posting in Q&A. In fact, when deploy Hybrid Azure AD-joined devices by using Intune and Windows Autopilot, the same device has two entries in Azure AD which is expected behavior. However, the Intune device is associated with the hybrid joined device in Azure AD. This can be confirmed when we compare the associated Azure AD device ID: For your situation, this is normal. Here is a link for your reference:
Hope the above information can help.
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