Each cross-vCenter NSX environment has one universal controller cluster associated with the primary NSX Manager. Secondary NSX Managers do not have a controller cluster.
As the universal controller cluster is the only controller cluster for the cross-vCenter NSX environment, it maintains information about universal logical switches and universal logical routers as well as logical switches and logical routers that are local to each NSX Manager.
In order to avoid any overlap in object IDs, separate ID pools are maintained for universal objects and local objects.