To begin, I stack one of the shuriken's above the other, whilst I put my dominant right hand through the hole in the shuriken's, grasping the shuriken's firmly. Since I stacked both shuriken's together closely, it would be difficult to notice that it is in fact, two shuriken's, and not one. Then, I swing my right hand forward, throwing both shuriken's at you, with one shuriken on top of the other, the second shuriken hidden in the shadow of the first, travelling slightly behind the first. The trick to this technique would be to hide the shuriken underneath's trajectory, coming as a surprise as the opponent deals with the upper shuriken's trajectory, though the real danger is the one below, which is mostly hidden in the shadow.Wesobi said that flash bombs don't work on Sharingans, so go bother him. >.>
And the best place to toss these will be BEHIND you, using a single hand.
Alright, let's move on to the first jutsu.
Take these huge shurikens and note how they are very much similar to one another. Then, proceed to throw them in a way so that the second one is hidden behind the first.
Do you the purpose of such a jutsu?
I suppose the purpose of this technique would be to conceal the real danger, which is the second shuriken, whilst it travels behind the first, hidden from the opponent, which is perhaps the trick to this technique. However, if the opponent is able to see both shuriken's, this technique loses all its benefits. In other words, the first shuriken is a diversion. Also, as the opponent needs to focus to see both shuriken's and defend against both, this technique is more of a diversion than anything else.