Well thank you vary mush Zero for the information.
I guess Zack is gone forever.
And I highly doubt Hojo intended to create another Sephiroth, because if that were the case he would simply start over injecting Jenova Cells into an unborn child. It seems like it would be a lot smarter, and therefore Hojo would do it, to just do what he knows works instead of trying to guess and create clones. I'm pretty sure Hojo was just setting up the Jenova Reunion predicting (and being right) what Sephiroth/Jenova would try to do.