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.
A player, 8 August 2007
Can the following abilities be used to attach the same item, thus having a reduced cost and drawing a card?
Three Man Alliance Plain - "Reaction: After one of your Personalities enters play, bow this card: Target him. Attach a card to him from your hand (paying all costs). If he attached a card, draw a card. "
Supply Outpost - "Bow this card: Bow this card: Produce 2 Gold. If this pays for a Personality, you may attach a Follower, Item, or Spell to him from your hand after he enters in play, reducing its Gold cost by 3 until it attaches."
Martin Lund (rules official), 8 August 2007
Can the following abilities be used to attach the same item, thus having a reduced cost and drawing a card?
Three Man Alliance Plain - "Reaction: After one of your Personalities enters play, bow this card: Target him. Attach a card to him from your hand (paying all costs). If he attached a card, draw a card. "
Supply Outpost - "Bow this card: Bow this card: Produce 2 Gold. If this pays for a Personality, you may attach a Follower, Item, or Spell to him from your hand after he enters in play, reducing its Gold cost by 3 until it attaches."
No. You resolve one or the other. By resolving one, you've put the card in play. That means the other one won't have anything to do.
You can see another recent example here.