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If you import a device, then run a discovery some fields may be overwritten. Model is likely the first one you'll notice. This is expected. Two screenshots are below of a device after import, then after discovery.
Note that this was an example only as the import was a Cisco Nexus and the discovered device was a Cisco 1841 router. I manually changed the serial to cause them to match.
After import.
After Discovery.
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