Both of them are PWM.
That means it is Dumping, or it is Not Dumping.
If it was dumping, it was dumping 85A.
If it was Not dumping, then 0A.
It may average out to 20A, but that does not mean it was not dumping 85A when it was dumping.
TS-xx manual, section 6.2
"The maximum diversion load current capability for the two TriStar versions is 45 amps
(TS-45) and 60 amps (TS-60). The diversion loads must be sized so that the peak load
current cannot exceed these maximum ratings."
6.4
"CAUTION: The diversion load must be able to absorb the full power output of the
source, but the load must never exceed the current rating of the TriStar controller."
The dump load is sized for 2500W, which is 85A.
Here is a O-scope pic of my ghurd controller. A few adjustments to the scales and your 2 controllers would look like this too.
It is dumping, or it is not. There is no half way between full Ohm's Law amps and 0A.
G-