I also have the same:
The current version is 2.0, released 2005-04-12
Congratulations, you have already signed the Ubuntu Code of Conduct.
If I click on signed, I get to my Code of Conduct version 1.1 I have signed. You can check it, and at the end you have a Deactivat button.
Click it, and then you can sign it again, using the usual method. This time you will sign the 2.0 version.
P.S. Sorry for the non-detailed answer, but I am in a hurry :)
I have managed to revoke my old code of conduct, and now I have signed the 2.0 version.
Your Code of Conduct Signature was modified.
= Ubuntu Code of Conduct v2.0 =
However I had some small issues;
For starters, I have deleted the old key I have signed the initial COC, so I generated a new one. Strangely when running the command :
gpg --clearsign UbuntuCodeofConduct-2.0.txt
the default key is taken. I had now multiple on my key-ring, so I wasn't signing with the one I had just re-registered on Launchpad's site.
The correct command to sign the COC with the chosen key is:
gpg -u <name of wanted key> --clearsign UbuntuCodeofConduct-2.0.txt
So when I finally managed to sign the COC with the wanted key, Launchpad wasn't accepting the response I was generating. Honestly I have copy/pasted the response at least 15 times, until it finally accepted it. :)
So there I go, now I have version 2.0 signed.