If the shared ip address is not a valid ip address on one of the devices, the configuration should be changed to remove it. The deviceIPAddressList attribute on the associated model will be updated within the next hour and the ip address removed.
If this is by design, then, if the device configuration supports it, the ip address used to send the trap should be changed to a non-shared ip address.
Following the instructions outlined in knowledge article "When a trap source IP address is found on multiple devices in Spectrum, the trap is processed on all devices with the IP" to exclude the trap from being processed on a specific model.