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.
I remember in Lotus, when a card required you to "target a Samurai Personality and a Courtier Personality", a single Personality with both traits could not be used to meet both requirements - but I didn't find this in the current Samurai rules.
Now, if an action has an additional cost of, say, "Bow a Personality" (thinking of Soul of Battle), and also has a cost of, say, "Target an unbowed Personality"), can the whole cost be paid with a single Personality?
The phrase "a [keyword 1] and a [keyword 2]" refers to two different cards, each with the relevant keyword. Example: "Bow a Samurai and a Courtier" is not fulfilled by bowing a single card with both Samurai and Courtier as keywords.
Taken from the Comprehensive Rules
Most costs or instances of mandatory targeting only preclude a single card pulling double-duty if they use a conjunction like "and."