When thinking about a double rifle, I find that hunting driven game, like wild boar, is the most important aspect thus the ability to make two or more fast shots is essential.

Therefore the ejectors or extractors play a role in making shot number 3 and 4, giving you the possibility to get the third and fourth boar on a driven hunt.

My father, who was several times skeet and trap champion of Denmark back in the 50'ties taught me to shoot duck's or pheasant with two shells in my left hand and reloading fast for a second doublet...

On a shotgun that is only possible with fast working ejectors and on a double rifle with Ejectors OR extractors but the brass MUST be with “Rand” like 7x65R, 7x57R, 30R Blaser, 8x57R, 9.3x74R and upwards.

The extractors I have seen in caliber 30-06 would have a little tap for extracting the brass so that you can remove the empty cartridge with your fingers by pulling the cartridge out, but it will not allow you to throw the cartridge out for fast reloading and a second go at the boars.
The cost of ammunition is only of interest for practice shooting, thus the idea of a second set of barrels in a shotgun caliber like 16 or 20 makes good sense as you can practice a few rounds of skeet every week with your double without breaking any budget.

Best regards, Peter Frost Hørlyck