JP, the one on the right is also a so-called “8 mm S&W Experimental”, but in fact is a .32 WCF specially loaded by UMC in 1900 for the Smith & Wesson .32-30 Hand Ejector 1st Model (1899).
Thanks Fede !
if I understand well the left one is experimental and the right one just a regular loading (no value !)
What is the story f the left one and value ,
My guess for the one on the left is .32 Smith & Wesson Revolving Rifle.