There is a /usr/bin/sage file in my PC, and I can use sage to launch sage9.0 normally:

It is not a soft link, because readlink /usr/bin/sage return nothing, and Now, I compiled a new version of sage10.0 from the source code, and
# ll /usr/bin/sage
-rwxr-xr-x 1 root root 26791 Feb 8 2020 /usr/bin/sage*
I can use /opt/sage-10.0/sage to launch it:

Now I want to use update-alternatives to manage my two commands(/usr/bin/sage, /opt/sage-10.0/sage), but:
# update-alternatives --install /usr/bin/sage sage /opt/sage-10.0/sage 100
warning: not replacing /usr/bin/sage with a link
# update-alternatives --install /usr/bin/sage sage /usr/bin/sage 200
<link> and <path> can't be the same
How should I deal with these two errors?