This is a different deployment of the same product [1]. Which, incidentally, was originally created by Aaron Swartz. The Wikipedia page[2] has a list of well-known deployments.
Thanks for pointing that out. I just watched "The Internet's Own Boy", the documentary about Aaron, and it is positively incredibly how many projects Aaron created or played a critical role in creating. An unthinkable shame that he left us so soon — one can only imagine all the things he had left to create.
[1] https://pressfreedomfoundation.org/securedrop
[2] http://en.wikipedia.org/wiki/SecureDrop