Why is this cron entry executed twice?

Question

*/5 * * * * my command

This entry works but every 5 minutes it gets executed twice, why?

In /var/log/cron it shows:

Answer 1

I had the same problem due to a double entry in conf file:

# grep /syslog /etc/rsyslog.conf /etc/rsyslog.d/50-default.conf 
/etc/rsyslog.conf:*.*;auth,authpriv,kern,mail.none      -/var/log/syslog
/etc/rsyslog.d/50-default.conf:*.*;auth,authpriv,kern,mail.none -/var/log/syslog

Clearly commenting one of the 2 solves the problem