Performance Management is integrated with a Data Aggregator (DA) and Spectrum as Data Sources. The Data Aggregator is also receiving inventory from a Virtual Network Assurance (VNA) integration. When all sources have contributed the device to the overall inventory, we see a duplicate of it in the DA Monitored Devices inventory.
DA auto discovery only takes place if the device isn't known to the DA. In this scenario when Spectrum syncs it to PC via the integration, during the next sync cycle DA then gets the new device if not known to it. The key here tripping things up is that the DA already knows it via VNA. As a result it doesn't get synced from PC again and no discovery attempt is made via the DA and SNMP.
Performance Management and VNA releases r3.7.2 and older
In the r3.7.3 release of Performance Management and VNA a switch was added that allows automatic discovery of the devices coming from VNA. This is seen in the r3.7.3 fixed issues list as follows.
Until upgrade to the new code is performed, existing VNA only devices in DA will require manual discovery via a Discovery Profile using the correct SNMP Profile to add SNMP support to the VNA device.
On r3.7.3 or newer releases with this new feature enabled users will no longer need to manually discover affected devices.