Perhaps.

For all we know, however, the 2200fps could be from a development load for the Mannlicher Schönauer M1910 (9.5X57MS) which was marketed by Westley Richards. The text of the ad does not specify a powder load or cartridge number and refers to it as a cartridge "adapted by Westley Richards & Co. after careful experiment". Several sources, including Westley Richards, indicate that the .375 Nitro Express Rimless was originally designed by WR.

Also, the '270' refers to the projectile weight in grains which is common to both the .375 RNE and 9.5X57MS as listed. The difference in velocity was due to different powder charges - 43 grains Cordite for the .375RNE, 45 grains for the 9.5X57MS.

To find definitive answers, one would need access to the original, accurately dated, documentation from the firms that designed the cartridges and that manufactured them.

From what I've found that would be Westley Richards - or not. It could be DWM, perhaps dating from 1908 - or not... . From WR's own 1938 catalog and others, however, we can see that the two cartridges coexisted for three decades with the 'Westley Richards .375 Rimless Express' loaded at 43 grains Cordite, the Mannlicher Schönauer 9.5X57 getting 45 grains. The 'Standard Ballistics of English Cartridges' table found in the 1939 Stoeger shows us the same cartridges at the same loads, lacking the 'Westley Richards' designation on the .375RNE and the velocity of the 9.5X57MS at 2150fps, not 2200.

Throughout its history the 9.5X57 has been called by several names by several manufacturers and worn several headstamps.

Click this link to see several such examples: http://www.municion.org/9_5Mann/9_5Mann.htm

Happy hunting.