Smarts IP is functioning as designed. To work around this issue, you can set the RigorousMACTest to TRUE using a Smarts DMCTL command as follows:
dmctl -s <IPDomain> invoke ICF_TopologyManager::ICF-TopologyManager insertParameter RigorousMACTest TRUE
It is not necessary to restart Smarts IP Manager to apply this change in the active environment. After running the above command, you can rediscover both devices in question and verify that both get discovered.
To make the change persistent across domain restarts, modify the tpmgr-param.conf file to set the value of RigorousMACTest to TRUE. The RigorousMACTest is set to FALSE by default.