i could understand if a zilliax version was played that created another and later hydration station brought both back.
I just can’t see how a single zilliax version getting doubled with that card is reasonable. i guess i should be happy it didn’t create 3? yikes! 
It has reborn, so it dies twice, so 2 are made. It will make three if 3 died.
That’s because of the Reborn keyword.
Zilliax dies and then comes back onto the battlefield because of Reborn and then must be killed again to vanish.
Since he technically died twice 2 Zilliax can come back since 2 died.
yeah that is just broken IMO. i assume people won’t bother using the Twin Module when making a zilliax build now.
I have ignored the calls for zilliax nerfs, when there were more things out there even worse IMO. when those “worse” things synergize like this it’s bad news.