Comment # 2 on bug 1130746 from Eric Benton

I can confirm the same behavior. 
I reduced the root and user crontabs down to 1 line each "* * * * * /bin/echo
"Hello from root/user crontab" and verified each crontab did in fact work
I then added a second similar line (copy/paste) and in no case did that second
line ever get run
I tried uninstalling and re-installing cron, rebooting etc nothing made any
difference.