I have to wonder about stuff like this, if we're just hearing the 5-10% component tolerance and tube differences.
Because pulling up the schematics of the Rev G's, the Dual and Triple are identical besides an extra pair of tubes in the power section. Not sure how that equates to "tightness" in terms of how it feels in the low end but I'd imagine unless you are playing at 150 decibels you can't possibly notice. I've never had both a Triple and Dual of the same model at the same time but I do right now, maybe I'll check a few values between them and see if anything is actually different that isn't noted in the schematics.
Same with the Multiwatts, same exact preamp spec with no changes between the Dual and Triple. So how would the Triple have a scoop? An extra pair of power tubes does not affect the pre-eq which is where shaping like that would be happening.
I think if you really were painstaking enough to go through the signal path and check every component to be identical measurements and used the same set of tubes in both amps (minus 2-3 tubes in the dual) they will sound identical. They even use the same transformers, so it's not like the usual argument that the transformers between 50w and 100w models are different like with Marshalls.
Keep in mind if a component has a 10% tolerance spec, say for example the Orange channel of a Rev G EQ Slope Resistor is 47k, it could measure as low as 42k or as high as 52k. So two amps with just that change alone are going to have a pretty noticeably different sound, then expand that across the entire circuit... but most people only ever play one or two copies of the same amp, and almost never in the same room at the same time through the same cab etc...