A Duplicate Post can happens when Steemit is down.

• Double click , a result of double post, one of the post must be amended. ( Best is to go back to your Home Page and check them, It can be Deleted; if there is no upvote or comment yet. )
• A Duplicate post can happen ,One resubmitted the same post.
  ( Not Allow )

You can have part 1 , 2 ...etc.. but not the same post.
A clear Tag must be In Place , ie if one is doing

• Testing
• Experiment
• promoting
• Survey
  ( We allow for this one )

Thanks for your questions , It help us to improve.