Formatting of script

Just enabled Elysia cron on the site and configured it to run a certain function at midnight with the following:

0 0 * * * functionname();

It isn't midnight (actually 4 in the afternoon), cron was run through /sites/all/modules/elysia_cron/cron.php file and the function defined above appears to have been called twice as I now have the resulting email twice.

Previously I had cron set up like so:

function modulename_cron() {
  if (date('H') == '00' && date('i') == '00') functionname();
}

And then had cron running */15 * * * *

Have I set up the script bit wrong or is there a problem with the module?