Devices configured to use SNMP v3 are required to have a unique SNMP engine ID, basically engine ID identifies the SNMP agent. If the devices do not have a unique SNMP engine ID, SNMP v3 does not function properly.
It might have happened accidentally or with some kind of sync.
If the SNMP engine ID is not unique it must be changed on one of the devices.
Caution: Changing the ID of the SNMPv3 engine invalidates the current SNMP users. The SNMP v3 encrypted passwords and passphrases depend on the engine ID, so if the engine ID changes you also need to recreate the user and accordingly you have to reconfigure the SNMP profiles in the SapphireIMS profile configuration.