Each certificate is a separate electronic document in which Let’s Encrypt attests that it was confident you are the legitimate owner of the names in the certificate when issuing the certificate. So there should be no problems unless (for example through some mistake you made in configuration) you are serving up a copy of the old expiring certificate to people from somewhere. If you later find you made such a mistake, simply fix it to use the correct certificate and the problem goes away.
Okay the second thing is, I'm using CentOS6 and get a Syntax Warning (deprecated) and the Warning: unable to check for updates. I check certbot-auto and now it use Python3.3 but the error sayed 2.6 is used. i cant remove 2.6 because yum need it.
The Output is the following (every time I run certbot-auto):
File "/tmp/tmp.XSYd4nJnWJ/fetch.py", line 114
print latest_stable_version(get)
^
SyntaxError: invalid syntax
WARNING: unable to check for updates.
/root/.local/share/letsencrypt/lib/python2.6/site-packages/cryptography/init.py:26: DeprecationWarning: Python 2.6 is no longer supported by the Python core team, please upgrade your Python. A future version of cryptography will drop support for Python 2.6
DeprecationWarning