multiple vcenter servers.
The scenario is as the following:
Nutanix Cluster A - vCenter Server A -- Prism Central A
Nutanix Cluster B - vCenter Server B -- Prism Central A
Best answer by MBates
Looks to be supported, vcenter instances already registered in prism element are auto imported. See link below for more info
https://portal.nutanix.com/#/page/docs/details?targetId=Prism-Central-Guide-Prism-v56:mul-multihypervisor-management-esxi-pc-c.html