Hey,
first, verify whether the Samba4 LDAP still contains entries for those two servers, e.g. with something like unvention-s4search --cross-ncs | grep -Ei 'sgfs2|sgfs3'. If they do, you can try removing the references with a little helper script:
/usr/share/univention-samba4/scripts/purge_s4_computer.py --computername=<hostname>
You should probably run that for both server names anyway.
The script is mentioned in the following knowledge base article:
https://help.univention.com/t/samba-4-troubleshooting/32
Kind regards,
mosu