I bought Twisted Sisters like 5 years ago when I first got into magic, and it instantly became one of my favorite tricks. However, I didn't really perform it much because it was gaffed and I don't like carrying around stuff with me especially if it can't be examined. So Twisted Sisters went into the magic junk drawer.
(fast forward 4 years)
John Bannon has done what magicians were waiting years for - create a version of Twisted Sisters that is examinable.

Enter Duplicity...

Effect: Same exact as Twisted Sis. but with aces.
Slights: Only one slight is used, and it's a slight that every magician knows (and if they don't - John teaches it in depth).
Difficulty: The hardest part is remembering the patter. You are gonna have to remember some patter, but it's quite simple to remember.
Practicality: EXTREMELY practical. You can so this trick for close-up, walkaround, and stage (if you have a projector bec. the cards are small - but you can always use jumbo cards).
Set UP/Reset : 3 seconds each.
Reactions: Worth a LOT more than .25
DVD: Very well made. And you get an AWESOME bonus effect which kills people!

Conclusion: If you don't have Duplicity, buy it. NOW. You won't regret it.

I reckon this is worth the 11.25. It is a one routine item, but there are some helpful, subtle insights into the way JB presents "guiding" the spectator so that it all looks like free choices. (Unlike Twisted Sisters, this set of cards isn't gaffed and can be examined). Also, he gives some helpful insights into the basic sleight and explains why different handlings fit different situations.

I was amazed by the video and when I got the package and saw how it was done I was almost disappointed by its sheer simplicity, but then became even more awestruck by its total deviousness. By the way the bonus trick that comes on the CD is quite strong as well--I was expecting something a bit more "throwaway" but it is a quality trick and both will leave your audiences scratching their heads.

"Twisted Sisters" by John Bannon is widely regarded by magicians as one of the best packet tricks of all time. But it does have a disadvantage: the cards aren't examinable at the end. The creator of the effect, John Bannon, later revised it to provide a more clean finish, in which all the cards are examinable by the spectators, and that revision is "Duplicity".

The overall effect of Duplicity is somewhat similar to Twisted Sisters, and also involves eight cards. You and a spectator each select a different Ace from your packet of red or blue backed cards. Then follows three surprising revelations: firstly the two chosen aces are revealed to be the only ones face-up. Then, these selected aces are revealed to have come from the other person's packet because they have a different coloured back. Finally, all the remaining aces are revealed to be blank.

The technical handling of this trick is quite straight forward, and just as easy as Twisted Sisters. However a much more delicate approach is required in the wording of the patter, since the spectator needs to make three choices throughout, and it needs to be made clear that they are all free choices. But when this is executed well, and combined with a good presentation, the final reveals are killer. Many magicians prefer Duplicity to Twisted Sisters because of the clean finish. An improved version of Twisted Sisters? Maybe, but either way it's a terrific packet trick that I can highly recommend. - BoardGameGeek reviewer EndersGame

Easy handling and fast to learn. I Practiced one evening and was performance ready by the next day. It should be noted that I am considered a beginner in magic with decent skills. I love that fact that you end completely clean with this trick. Has a nice build up of surprises as you reach the climax of the trick. The instructional video is nice and clear and even includes a bonus trick.

Unlike Twisted Sisters, there are NO gaffs. Just regular cards and some brilliant wording. This is mentalism at its finest!

love it its like the b wave but 10 times beter they can examin all of it, you end up clean and easy to do. but be careful how you word it ....follow the dvd and youll have no problem you will love it.

Essentially the effect of Duplicity and Twisted Sisters is the same. But Duplicity is gimmickless. Instead it uses a simple principle in mentalism. It does require more scripting but it's not difficult. I have both effects and it depends on the setting to decide which one is suitable. Overall, if you like Twisted Sisters but don't want to use gimmicks, get this.

This is a elegant magicians effect...it has class. Its simple, short, sweet...brilliant. Cards are examinable. Enough said. Add this one to your collection.

John Bannon have never failed us, this trick is so simple yet so strong. Very easy to perform, no sleights of hand is needed, end clean and everything is examinable(this is what beat twisted sister). The price is way too low for this gem in my opinion.