This argument is based on the fact that the save from a duplicate is not a card effect. I can not find any language in the FAQ that supports that the save from a duplicate is a card effect. If anyone finds it, let me know.
Section 3.7 does not support that the save provided by a duplicate is a character ability:
"(3.7) Card Abilities "Card abilities" (i.e. "Character ability," "Location ability," or "Attachment ability") refers to anything in a card's text box, except for traits, keywords, and flavor text. "Card
abilities" also refers to any abilities (again, keywords and traits are excluded)
gained by card effects
"
Emphasis mine. Section 4.2 has a parenthetical statement that claims the duplicate is a character ability, but parenthetical statements do not alter the meaning of a sentence. Per wikipedia, parentheses "contain material that could be omitted without destroying or altering the meaning of a sentence".
"(4.2) Duplicates
The text from page 19 of the Rulebook should read: “If one of your unique cards is about to leave play, as a triggered ‘Response:’ effect, you may discard an attached duplicate to save the unique card from leaving play. This includes, but is not limited to, an effect that kills, discards, returns the card to hand, deck, shadows, or removes the card from the game.”
Playing a duplicate is not considered to be playing an attachment. Duplicates may not be played during setup.
Using a duplicate to save a character is considered to be a gained triggered "Response:" action. Thus, it is treated as a triggered effect and may be canceled, but because it is gained (and therefore an ability of the card attempting to use the response), a character who is "immune to triggered effects" can be saved by using a duplicate, as a card cannot be immune to its own abilities ."
Note the end of the sentence. 3.7 is the ultimate source for determining what is a card ability as far as I can tell. 3.8 has some additional info, but continues to use the "card effect" language. There is now clear inconsistency in the FAQ as to what does and does not constitute an ability.
This results in the question:
Can a card that cancels character abilities be used to cancel a saved provided by a duplicate? If yes, why?