You are right, they are 1P+N even though Hager sometimes refer to them as 2P. Oddly enough the 4P ones appear to really be 4 protected paths for over-current:
RCBOs B & C Curves 2 & 4 Pole
www.hager.ie
I don't know. You would need to check the local regs to see what is required.
My French is not up to decoding this to see if it really is 2P instead of 1P+N, and the picture is not quite good enough for me to see if the little printed schematic is showing the thermal/magnetic trip on both paths, but maybe someone on here can tell:
A la recherche de Interrupteur différentiel 2P 25A 30mA AC à bornes décalées SanVis CDS722F? Retrouvez toutes les informations pour Protection sur le site officiel Hager !
hager.com