If player A has 2 Zenmaines on his side of the field, and player B activates a Dark Hole (or any other mass destruction effect) with a totally empty field, and player A decides to save them both, then in the end phase player A cannot select the same Zenmaines as the target for both Zenmaines' destruction effect unless this target remains on the field after the 1st one's destruction attempt.
Zenmaines with 1 material + Zenmaines with 1 material.
Dark Hole.
Zenmaines detaches + Zenmaines detaches. (Both with 0 materials)
End phase, both are destroyed.
Pojo link here
Zenmaines with 1 material + Zenmaines with 1 material.
Dark Hole.
Zenmaines detaches + Zenmaines detaches. (Both with 0 materials)
End phase, both are destroyed.
Pojo link here