Two host with single user account in 802.1x with FreeRadius

Hi All I find some issues with FreeRadius and look for some suggestions. I have two hosts, connect to a dumb switch. This dumb switch is connect to a Cisco switch (production network). 802.1x is configured in the Cisco switch. "multi-auth" is configured in the switch interface, so it supports multiple MAC addresses in the single port. As long as I use different user account in the two hosts, the 802.1x authentication works fine. If I uses the same user account/password in tow hosts, the 802.1x authentication is not working. Is it a Freeradius issue or switch issue ? Is there any way to fix it ? Thanks in advance. Regards