In ITAM 12.9.... do not allow the creation of a new asset record if a serial number has already been used in another asset record.
That's correct. APM considers the serial number as one of the unique values while you go through the asset registration process. In reality, every physical asset will have a unique serial number. Is your question more from Virtual asset point of view? Can you elaborate more on the question and context for us to know more details and see if we can address the complete scenario ?
Serial number is one of many fields that ITAM uses to define an asset as UNIQUE. It is not the only one. You could in theory have the same serial number, but different Host Names, and they are considered as two assets. Through the use of Hardware Reconciliation, you can match discovered assets to owned assets on a common field, such as serial number.
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