If a card states that if you use a no cost ability you may copy that ability and choose new targets, does it copy death touch which is a static ability.
I would need to see a card and situation to help you more but from what it sounds like no. Now if you cast a spell from the top of your library such as {serpents gift} and had {melek, izzet paragon} out, then yes, you can give 2 creatures deathtouch.
As previously mentioned, a card to reference would be really helpful. I don't recall hearing of this particular ability.