Yep, there has been a lot of fugly shotgun to double rifle conversions done on a variety of actions over the years, by people who don't understand what a double rifle is or should be.

Luckily here in Aus we have had a small number of gunsmiths/gun makers who did know how to do it right.

Guys like Ron Webb, Jack Millar and Alex Beer.

Alex Beer has built DR's with slender lines and correct balance completely from scratch, not shotgun conversions.

Ron Webb and Jack Millar have done DR conversions using the Ruger Red Label 20 gauge blued and/or stainless frame, which have been done right.
I've personally handled and shot 3 of Ron Webb's Red Label doubles and they are very well proportioned and balanced, and are very fast to get on target.
Of course these guns were built many years ago when there were very few DR's available on the market.
Things are very different these days in the DR world with bucket loads of double rifles available on both the used and new markets.

Things were very different back in the 80's and 90's when even projectiles, cartridge cases and reloading dies were not easily available for the big British cartridges.

Those who have come into the double rifle world in the last 15 years or so, don't realize how easy they have got it!