It sounds like your putting your carto through quite the torture test! I believe all those DC cartos that come stock with the tank are 1.5ohm, running at near 6 volts (even with a DC) seems pretty high, that could most definitely account for the burning.
The quick vaping, without letting the carto "rest" for a bit between drags can also contribute to this. At such high voltages, with a dual coil carto, your boiling a LOT of juice at once, probably drying out the filler material immediately surrounding the coil, and the material can't wick more juice from further away quick enough to stop the burning. I'm guessing that the carto also isn't getting enough juice fast enough from the tank, even with single hole cartos at moderate power I see at least 1-2 little bubbles on every single drag. Keeps the filler nice and wet.
If you are pumping a lot more power into the thing (and a lot more vapor out) that tank needs to supply a lot more juice to your carto, which it doesn't seem to be doing for one reason or another.
From what I can tell you just kind of have a "perfect storm" type situation where every little issue with a tank that can fail did fail. Not enough juice into the carto, not enough juice into the coil from the carto, slighty thicker than normal juice, high power, etc.
Cartos can vary from one to another. I usually buy large amounts of cartos whenever I place a carto order, and every now and again I'll get a carto, that straight out of the box will flood 100% of the time, others will fail to suck much juice from the tank at all and I have to suck on the tank several times without firing the coil just to suck up enough juice. And these are all the same exact carto, some work badly, most work good.
So it could be a faulty carto, or it could be the conditions you are subjecting this carto to that is causing the burning. It's possible even single coil cartos will give you this same issue if you are pumping tons of power into a less-than-soaked carto.
You can just get single coil cartos for your current tank, but if you are looking at getting another tank, then I'd suggest the locking tank, called the Artemas at some retailers. Takes the same cartos as your current tank (which means there are cartos with every combination of coils, ohms, and holes you could think of) but the carto is completely locked into the tank, so it can't spin and the tank can't fall off. Madvapes as well as many others carry this tank.
I also know that Baditude will suggest the IBtanked glass tanks when he makes his way back to this thread (
) which I find to be very good tanks as well. I have an xl length 19mm and a short length 19mm right now, absolutely love them. I did chip one of the glass tubes but that's another story and was user error. The SS endcaps are super nice too.
