A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
Does additional Doji Katata allow the use of the Favor's Battle ability to be used for each Doji Katata you have in play per his trait?
Doji Katata 0F 1C 8HR 8GC 3PH Crane Clan • Courtier
Katata cannot attack or defend. You may take Favor Battle actions one additional time per turn.
Political Home Battle/Open, [Bow]: Take the Imperial Favor.
"I think an important point has been overlooked."
IvE1/IvE2
I highlighted the relevant text for consideration.
Does additional Doji Katata allow the use of the Favor's Battle ability to be used for each Doji Katata you have in play per his trait?
I highlighted the relevant text for consideration.
Yes, multiple copies of the trait are indeed cumulative.
Had that not been the intent, the trait would've said, "a second time" (rather than "one additional"), because there can only be one "second time" no matter how many copies of the trait are in play.