We discovered that the IP address of the new device was hidden within the USMOtherIPAddress attribute of an existing device. The reason that the IP appears within that attribute is because of a valid ICMP Probe (layer 3) configuration. The setup of the ICMP Probe causes the IP to appear within the ipAddrTable:
However, the IP address is not the primary for this device, it is just a side effect of the ICMP Probe that was configured. The ACTUAL device with the primary IP of 10.10.150.4 now cannot be discovered within Spectrum because it exists within the USMOtherIPAdress attribute list.
Trap Based discovery only looks in the IP cache of the SS. It does not do any further verification so if the IP is already know by Spectrum, Spectrum will assert the event on the model that already has that IP.
Release : 21.2
An enhancement request has been opened for a future release of Spectrum to verify the IP is a true duplicate and if not create the device.