RG Live WotLK 3.3.5a

Those are duels and have nothing to do with whether you're PvP flagged or not. Also, participating in a duel won't flag you for PvP, even if you are up against someone of the opposing faction who is also flagged. Duels don't end in death, the first one to be whittled down to 1 hp is declared to be the loser of the duel. BUT if the other player uses fear, mind control, or other similar abilities that cause you to lose control of your character, they can force you to take "real" damage by running you into hostile mobs OR running you off a cliff/into lava. If this happens, and you take enough damage to kill your character from where the duel damage left off, you will die.

There IS a way that enemy players can use a duel to trick someone into flagging themselves. This usually involves inviting someone of the opposing side to a duel while flagged for PvP, and then mid duel, forcibly canceling the duel while you two are still fighting. This generally means that the non-flagged player will land a hit or two before they realize the duel flag is no longer up, meaning they damaged a PvP flagged player on the opposing side and therefore flagged themselves. This leaves them open to attack (and death) from the other player and any of his friends that may be hiding nearby.

http://us.battle.net/wow/en/forum/topic/5271501898

Der Fehler tritt auf, sobald ein nicht PvP-geflagter Spieler einen PvP-geflagten Spieler in einem "sicheren Gebiet" zum Duell herausfordert.
Bzw. in der open world, wenn ein PvP-geflagter einen Spieler mit ausgeschalteter PvP-Flag duelliert und dieser ihn im Duell angreift.

By Gauldion on 2010/05/15 at 10:10 AM (Patch 3.3.3)
I was sent a duel invite and I accepted. It was by a Tauren Druid with 5.6k gs.

Once I accepted, I noticed he had a BElf Shadow Priest with him, he had 2k gs.

Once we were dueling, I saw the Druid's name and bar go from red to yellow. I kept attacking but then he killed me. It wasn't like he won and I had 1hp left like usual with the begging for your life emote.

I was actually dead and had to spirit walk back to my corpse to rez. How was this possible? <I am in a PvE ream>

Edit: I had another thought after posting, could it have been the Shadow Priest sent his shadowfiend to attack me once I was flagged? Is this possible?

By Shirash on 2010/05/15 at 10:48 AM (Patch 3.3.3)
What does gearscore have to do with anything?

Anyway, if you dueled someone from the other faction and, as it sounds like, he toggled his PvP flag on during the duel, it would have turned your flag on too since you were attacking him. Which means that you were killable. It's a cheap tactic employed to get free honor.

By aFluffyFartBall on 2010/05/15 at 6:17 PM (Patch 3.3.3)
Ahhhh the old /yeald trick,,, Oh The memories. Gotta love duelling an alliance and /yielding half way and they attack you, its funny when they just die and look at you like 'WTF MAN'

http://www.wowhead.com/forums&topic=156369/killed-in-a-duel-how

gegenquelle.