Druid Dots
 

Currently, when one druid casts swarm on mob, the other druid's swarm will remove it and refresh it. I thought the separate dots would stack and dots which had previous lines the strongest one would kill.

If you have 5 druids attacking the same target, only 1 swarm dot will be active on the target at any given time. Not 1 per druid, just 1 total.

Yes. I thought each druid's dot was coded separately so that you can land 5 stinging swarms. Otherwise, how useless are druids on raids as dps? Other than DDs

that's how the game works. think of it like this...

level 40+ dot classes casting dots that tick for 100+ per tick
raid boss mobs have 32k hp

do the math because i don't care enough to

Well, they begin to stack. When? I am unsure. In Velious for sure. So think of your math this way, flawed.

They never stack on players only on raid targets. Not sure when they started to stack on raid targets either but I thought luclin?