Guild Wars 2

What happens if a boss is getting the “burning” or “poisoning” condition from multiple party members?
Will he get burned twice or does only the damage from one burning apply?
And is it from the one who cast it first or the one with the higher condition damage?

The durations will stack.
For instance, person A applies 4s burning with 1200 CD, person B applies 5s with 0 CD.
The boss will take 4s of burning at 1200 CD, because it was applied first, and then another 5s at 0 CD.
If the application order was reversed, it would take the 0 CD burning first, then the 1200 CD.
And this is why conditions are so awful against event champions and world bosses. The damage output is hardcapped, regardless of the number of people applying it, and it can take a long time for your damage to even affect it due to having to wait in line.

explained here

Oh I see.
I was just wondering because me and my friend both saw the condition damage number popping up. So i guess one doesn’t really apply then.

Awesome.6120:

explained here

Oh. Oops, so I was wrong.
The highest damage one will take precedence over the others, but the others will still stay on there once the highest damage one runs out.

I believe that is only the case when there are two unique sources. When there are more than two it works like you described in your first post.

“Oh I see.
I was just wondering because me and my friend both saw the condition damage number popping up. So i guess one doesn’t really apply then.”

If you are both seeing numbers pop up then you are both doing damage. There must have been another condition on the mob or something.