New Redemption Grab Bag now includes an assortment of 500 cards from five (5) different expansion sets. Available at Cactus website.
All multi-color cards are limited to 1 per deck, no matter what type of card it is. That rule takes precedence over the 3 per deck rule for curses.
The REG and Rulebook at the moment ONLY say multicolored characters and enhancements are limited to 1. And since multicolored sites are not limited to 1 I see no reason, without a rule change, that a multicolored covenant or curse should be limited to 1
When he mentioned the card during playtesting, I'm pretty sure Bryon said it was multicolor to limit it to 1 per deck. Guess the rules update either was decided against, or still needs to happen. Maybe when the limit becomes four enhancements...