Can you special summon two cyber dragons at the same time using their ability?

You cannot special summon two Cyber Dragons at the same time using their ability. Here's why:

* Cyber Dragon's effect: Cyber Dragon's effect states "You can Special Summon this card (from your hand) by sending 1 Cyber Dragon from your Deck to the Graveyard."

* Summoning rules: You can only Special Summon one monster per turn unless a card effect specifically states otherwise.

Therefore, even though Cyber Dragon's effect allows you to Special Summon it from your hand, you can only do so once per turn.

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