ServiceNow Discovery creating a new CI even though an existing CI has the same Name

[MOHAMEDIMRM]

Hi ServiceNow Community,

I am facing an issue with ServiceNow Discovery and CI identification/IRE.

We already have an existing CI in the CMDB with the same Name as the device being discovered. However, when Discovery runs, instead of updating the existing CI, it creates a new CI.

The situation is:

1. An existing CI already exists in CMDB.
2. The existing CI has the same Name as the device being discovered.
3. The existing/old CI does not have a Serial Number populated.
4. During Discovery, the device is discovered successfully and a Serial Number is obtained.
5. Discovery creates a new CI instead of updating the existing CI.
6. This results in duplicate CIs for what appears to be the same device.

Identification Rule configuration

I checked the Hardware Identification Rule, and the following active identifier entries are configured:

Identifier Type Priority
1 . Product Instance Identifier Standard 90
2. Name Standard 95
3. Refer to lookup table – Serial Number Lookup 100
4. Serial Number Standard 200
5. IP Address Standard 350
6. MAC Address Lookup 400

So, Name is configured as an active identifier with Priority 95.

My question is: if the existing CI has the same Name, why is IRE not matching the discovered device to that existing CI?

Could the fact that the existing CI has no Serial Number, while the discovered device has a Serial Number, cause IRE to create a new CI?

I would like to understand specifically how the above Identification Rule is evaluated in this scenario.

Questions
1 .Does IRE require all active identifier attributes in an identifier entry to match, or can it match using Name alone when Name is configured as an identifier?
2. Since Name has Priority 95 and Serial Number has Priority 200, should the existing CI be identified by Name before Serial Number is considered?
3. If the existing CI has a matching Name but no Serial Number, and Discovery provides both Name and Serial Number, why would IRE create a new CI?
4. Does a missing Serial Number on the existing CI affect the matching behavior even though Name matches?
5. How does the "Refer to lookup table – Serial Number" identifier entry affect this scenario?
6. What IRE/Identification logs should I check to determine exactly which identifier was evaluated and why the existing CI was not matched?

I would appreciate any guidance on how IRE evaluates these identifier entries and why it would create a new CI in this particular scenario.

Thanks!