Michael Schumacher wrote:
I just wonder if anyone has come across this curiosity? Or can suggest any possible cause.
Did you edit one of the jobs? Some Editors (joe) create a file with an "~" at the end as a backup. If you edit one of your cronjob-scripts in /etc/cron.hourly/ , you may create a second file that will be run by cron too. This happened here some time ago and it took some time to figure out the reason.
Thanks for the suggestion. I haven't edited any of the scripts in /etc/cron.hourly . Also, I checked and found that cron.hourly starts twice before any of the scripts starts. Each of the scripts then runs twice.