Dell M1000e chassis shows up as Asst Tag name under RAC group instead of DNS name

I have 7 Dell M1000e chassis in OME. All of them are showing with their DNS name under RAS group but only 2 are showing with their Asset Tag number instead of DNS name. I checked and double checked and compare setting between these two chassis and rest of the chassis. I don't see any difference. I do see this error message in application logs in OME:

"Discovery is re-using the database entry for Device Dell Rack System - 8L43HJ1
based on name only. Either discovery could not obtain MAC Address information
for the device during a previous discovery or there are two devices on the
network with the same name."

and this

"Device name change has been detected (old name: txpla02dellch02.parsons.com, new
name:Dell Rack System - 8L43HJ1, internal ID: -909368844)"

I made sure there are no duplicate MAC conflict.