I recently had to modify the DNS entries on a several SRM appliances, my first port of call was the GUI, after making my modifications I found that the appliance would not remove the old DNS entries, it just added the new ones to the list.
This shows 4 entries on the GUI after I attempted to update old entries with new
Here's how I managed to work around this....
First enable SSH access from the GUI interface
Connect to the appliance using Putty or similar and navigate to /opt/vmware/share/vami/
From here run ./vami_dns to confirm there are indeed 4 dns entries registered
Next run the command: sudo ./vami_set_dns 10.x.x.x 10.x.x.x to correct the DNS entries to your required values, and run ./vami_dns to check new entries have taken.
Lastly access the configuration via the GUI to ensure the changes are also reflected there
I've had this on previous versions of the SRM appliance too and it doesn't look like there is any fix at the time of this post, hope this helps.
Thanks for reading