Right now we can have one SSO with multiple vcenter servers connected to it but not an inventory service with multiple VCs. The data present in the inventory database is taken from the vcenter database, if you connect multiple vcenter with one inventory service then there will be chances of duplicate data which will again give us a trouble. Consider you have a host named as ESXi01 in VC1 and VC2 in turn the vcenter db will have the corresponding entries, when inventory service database sync up with the vcenter databases, there are chances of duplicate entries which will cause issues.
Regards,
Suresh
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