ssh key conflicts

[Martin Sebor <msebor@gmail.com>]

Lately, every time after I do git pull from glibc and I git pull
gcc I get this:

Warning: the RSA host key for
'gcc.gnu.org' differs from the key for the IP address '8.43.85.97'
Offending key for IP in /home/msebor/.ssh/known_hosts:18
Matching host key in /home/msebor/.ssh/known_hosts:1
Are you sure you want to continue connecting (yes/no)?

So I go and delete the offending key, but the next time I pull
the warning is back, and unless I delete the offending key I get:

Connection closed by 8.43.85.97 port 22
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

After I do delete it I can pull gcc fine but when I try to pull
glibc I get this:

The authenticity of host 'sourceware.org (8.43.85.97)' can't be established.
ECDSA key fingerprint is SHA256:4bqfulMjMg7/L/38MJBw7mVMMu6EH+3MgMitrCRdFho.

This didn't use to happen.  I read various suggestions online (in
addition to deleting the offending key as I've been doing also to
add CheckHostIP no in my ~/.ssh/config) but before I use them let
me ask:  am I doing something wrong and/or what is  the recommended
cure for this in our case?

Thanks
Martin