If I already has one Dragon Knight in play, I ambush a second Dragon Knight.

Could I trigger the response twice? (One from the card I just play, the other from the card already in play)

Tks a lot.

No. A card that refers to itself by title does not refer to any other cards with the same title unless it specifically says so.

No. The self-referential rule prevents this. A card that refers to its own name only refers to that specific card.