Duplicate crontab entries

hi guys. can someone tell me what will happen if there are two identical crontab entry for an application. For example
03 23 * * 1 /usr/vt/crondemo
03 23 * * 1 /usr/vt/crondemo

will the file crondemo run twice, once or wont run at all??

Why won't you try by yourself ?

My bet goes to the first choice as I would consider 2 and 3 as bugs.

The reason i asked this question in this forum is that it is behaving bit unpredictably on my system. I have a big application which got duplicate cron entries. SOmetimes it just runs once while other time it run twice and produce only one output