I'll be honest, Kabuto's mystery doesn't make all to much sense for me.

Sure, reanimation and edo tensei tag makes sense...but...

You can only reanimate people that are already dead. And the sacrifice doesn't die until after the jutsu is released.

So a living Deidara got reanimated into himself.

...Maybe...it should be that he reanimates them as a random Edo Tensei person (Deidara, Sasori, Itachi, Nagato, Kakuzu, Madara, Gari, Pakura, Haku, 7 swordsman, the edo jins, etc