MobilePush contact has multiple Device IDs for a single physical device

This is an expected behavior and there is no action needed. A Device ID in Marketing Cloud is a unique identifier for a mobile device automatically generated by the SDK. There are a few scenarios in which a contact's Device ID can change, even though they may have the same hardware.

• The Device ID will not persist an uninstallation/re-installation of the application: a new Device ID will be generated.
• The Device ID will not persist a consumer’s clearing of application data.
• The Device ID will not persist a consumer’s factory reset of their device.
• The Device ID will not persist when restoring from a backup.

Note that there are some scenarios that will not result in a new DeviceID:

• The Device ID will persist through platform upgrades (version x of OS -> version y of OS).
• The Device ID will persist through SDK updates unless expressly called out in the release notes.