I have not seen this happen myself - unless there really is an IP address conflict.
I assume there is no chance there are two DHCP servers on the LAN?
Are both devices configured to use DHCP, or is one/both using a static IP address?
You could try and take a packet capture from the LAN side of your Meraki device to ensure that there is differently not an IP Conflict issue. Trying rebooting your Meraki device to clear any ARP cache or alternatively you may have to wait for it to clear itself.
You could also attempt clearing the client usage data (If you're using an MX device) by following this guide - https://documentation.meraki.com/MX-Z/Monitoring_and_Reporting/Clearing_client_usage_data_on_the_MX_...
We had a similar case generating alerts. A Thinkpad with Ubuntu. DHCP was assigning an IP to both NICs, wifi and ethernet. But if I understand correctly, the MX100 was also attributing both IPS to each NIC, resulting in alerts. Mind bending.