No reason to by a pair. Just do a two barrel set.

I did not like the " Germanic" stocks on the Merkel and Heym. The Kriegoff safety is really a cocking piece and not a safety.

That leaves the Chapuis and Vernon-carron. Chapuis makes their small frame SxS in 9.3x74r and 7x57r. Their medium frame is made in 9.3x74r and 7x65r.

I choose the Chapuis based on price, I could get a two barrell set in a Chapuis for what a single caliburs VC gun costs.

Doubles are very subjective, try shooting one from each manufacturer and by the one you like the best.