Stacking Fast Cast/Recharge Time?

Ok. say that you have a one-hand weapon that gives 20% chance faster recharge or casting, and you have a focus that gives 20% chance for both of the same attribute type. Do these numbers stack to make it a 40% chance of fast cast/recharge?

Here:
http://www.guildwarsguru.com/forum/s...ad.php?t=58750