Flightaware shows the owner is a law firm (that also handles aviation accidents).
Oh, the irony...
Not familiar with the Navajo, but many of the bigger twins would be close to gross with full fuel and more than two people.
It appears that they came in from Craig and did a really quick turn, probably not enough time to have added any fuel.
Also, even if a Chieftain has gained a couple hundred pounds since it came from the factory, it should have a useful load of ~2500 pounds. 192 gallons (max fuel) would be a bit under 1150 pounds, leaving 1350 pounds for people, or over 400 pounds per person in this case. So, I doubt they were overgross.
I always thought that the reason that twins are better than singles is that in case one engine fails you can still fly and land on the other.
As with all aircraft, singles and twins, performance depends on a number of factors such as weight, CG, density altitude, etc. Generally, twins have a published single-engine service ceiling - Defined as the altitude at which they can only maintain a 50 fpm (yes, fifty) climb at max gross, aft CG, clean configuration, etc.
But, that's in a standard atmosphere, with an accurately calculated weight and CG, with a pilot who is proficient, on a new airplane.
