When looking at the Inventory of a MAC device, the Computername field will show the correct value while the Device Name and/or Display Name will show the name of another Windows device.
The Computername field is actually being reported by the Inventory Scanner on a MAC, based on the System Preferences > Sharing setting. The Device/Display name is the result of a nslookup for the IP address of the MAC (IP Hostname) on that device.
Most Windows DNS environments however, don't allow MAC's to update the DNS record, MAC's being 'non-secure' devices.
So what happens is, that a Windows device holds an IP address, is turned off for a while and DHCP hands out the address to a MAC. The MAC will try to update the DNS record for that IP address but fails, so the Windows device will stay registered in the DNS as belonging to that IP address.
More information on the Microsoft DNS setting can be found here: Allow Only Secure Dynamic Updates
Article based on a community post by Northice