Has the Mongoose Black Diamond 2 Frame been released?
Answer No (as of 2018-02-07)

There is a mongoose Black Diamond Double in 2008 which looks like this, but the pivots are in different places.



Second data point is that the top google match for "mongoose black diamond 2" is this question.  So that is a good indication that it doesn't exist by that name.

Its very hard to prove the non-existence of something.