Scripting

The "duplication" is happening, because the device lacks the necessary data to match it to an existing device in the Database, hence, a new one is created.

So:
1- you are NOT retaining their KUID (A task is NOT being used in the Imaging solution, to retain the current KUID before nuking the Disk).
2- during the re-image process you are changing hostnames (The device is reimaged but it ends up with a different hostname).

When the KACE SMA scans your hard drive, it looks for a KUID, if that KUID is associated to an existing record, the record is updated.
If there is no KUID, a new one is created with a new record. (hence the dupes).

LOGIC:

SMA: If you replied "NO" to all of these checks, you MUST BE a New device, Time to create a new record in the DB and consume a license seat,Bye.

NOTE: If you are Imaging with the KACE SDA Appliance, it has a built in task to retain existing KACE SMA Agent KUIDs, preventing the duplication from happening, even if the hostname is altered. You might want to check the KACE SDA Administrator's Guide.

UPDATE, JUNE 2022:
KACE SMA 12.1.x  now let's you modify this logic, I would suggest checking the KACE SMA's Administrator's Guide

So as a follow up to Nico’s brilliantly explanation, if you are blowing away the KUID and you want to auto clear up your inventory I would recommend the following, use you MIA settings to delete inventory after 30 days.

Also set up your link between Inventory and Asset, in the Device asset type, by creating a serial number field in the Device asset type, linking that field to the Inventory BIOS serial number field. That will ensure if the same machine checks into your SMA, without a KUID, the serial number link will link the inventory record back to the same asset record, showing the asset name has changed.

This will prevent multiple assets being created for duplicate inventory.