Yea the duplication glitch is patched in this update but a weapon duplication glitch has already been figured out. It requires a few extra steps but has been figured out.
A item duplication glitch is sure to come out in the next few days I'm sure. Nintendo patched it so you can't trick the game with y+b anymore. Also you can't get the unbreakable master sword anymore but if you already got it then your good.
I would update as it fixes quest and other bugs.
Actually Blaines on youtube just put out a new item duplication glitch. Check it out
Turn off Auto Updates. I even went as far as to just delete my Wifi settings until I beat the game. The game is great, but grinding for everything can be a chore. I am perfectly OK with duping.
I heard this update patches the duplication item glitch and some are recommending not to update.