No you only get each bonus once, but they unlock in tiers for each part worn.
1 Piece - Wear one item to gain that bonus once.
2 Piece - Wear two items to gain that bonus once.
3 Piece - Wear three items to gain that bonus once.
etc. etc.
Also be aware that bonuses only apply whilst weapons are active.
So if you have four parts of a set as amour and one as a weapon on your first bar, if the weapon on your second bar isn't the same set you'll lose that bonus when you're on the second bar.
Hopefully that helps, ask if you have any follow up questions and I will do my best to answer.
@Turelus - EU PC Megaserver "Don't count on others for help. In the end each of us is in this alone. The survivors are those who know how to look out for themselves."
You get the bonus for having two pieces of your set. This means that with crafted sets, you can use the full five bonuses from one set and have three or four of the bonuses from another set depending on your weapons. Dropped sets can also include jewelry, so with dropped sets you actually have the possibility of having two completed sets and two item bonus for a third set.
Former Guildmaster of the Legion of Mournhold XBL: GuyNamedSean PC: GuyNamedSeanPC
It can take a while. I am three years in and every now and then I still stumble on something new.
As long as you keep asking questions and checking things up when you're not sure you should do pretty well though.
@Turelus - EU PC Megaserver "Don't count on others for help. In the end each of us is in this alone. The survivors are those who know how to look out for themselves."