Cannot compare a Hemi 4spd Daytona to a Hemi auto Cuda convert.
Two completely different arenas.

Not surprised by prices.
The buyers chasing that level of Hemi Mopars today have plenty money.

https://www.mecum.com/lots/502693/19...-hemi-daytona/

https://www.mecum.com/lots/1122716/1...-hemi-daytona/

https://www.youtube.com/watch?v=8WYh9EMxSvI

2 mill profit in two years. In my opinion this is an outlier and questionable if it has original drivetrain.

Neither had a very desirable color combo.

at that level is the buyers premium negotiated ?

Only if they’re having trouble meeting a previously agreed upon reserve- ie the house will kick some of their calculated fee to the seller to facilitate a completed deal. Otherwise there’s no reason for the house to bend, and I wouldn’t expect them to-their party gathering is contributing to the result as much as the car when you get into some of these unexpectedly high bid scenarios.

so Dana just scrapped a cool 1.5 million from the sale of these 5...?

Chevy folks [with the exception of 66- 68 SS chevelles] are used to the VIN telling you basically nothing.
Cowl tags are sorta worthless also.

Not so on either count with Mopars.
VIN tells you EXACTLY what motor came in car.
Fender tag or tags tell you exactly what came on car.
Build sheets are common in Mopars also.

"Born with" is secondary to proper dates- numbers on Hemi Cars.

Heck of a lot easier to fake a LS6 Chevelle than a Hemi Mopar.

I'm going to note that while musclecar era Mopars and Fords have relied much less on "numbers matching" born-with engines to prove their provenance, as these cars get more expensive I am seeing "numbers matching" engines becoming more important to buyers, probably for bragging rights. The value uptick for original engine in 428CJ Mustangs and Hemi or 6 pack cars has increased over the last decade and buyers concern for it has grown. IMO.

That's revenue, not profit. Not to say he doesn't make a LOT of money, as I'm sure he does, but there's also a LOT of expense in producing these auctions.