[heckanoobs]

I've heard the movie plot twins phenomenon is because multiple studios will want a script and start assembling a team around it but one will outbid the other for the rights to the script. The losing studio will then pay a ghostwriter to create a similar script so they can continue with their plans.

Another theory is a lower budget production produces a similar movie to kind of 'draft' the marketing success of the main movie. These are called mockbusters

[logosmonkey]

In this case I think it's just closer to pure coincidence, or sharing the same zeitgeist. I was heavily involved in the indie comic community for a long while and we would see this all the time. You would write a script and start talking to other writer friends about it and they would mention another book that was nearly identical or also be working on a near identical script. It's weird but just happens in creative fields.