There appear to have been three types of 12.7x44R cartridges produced (SC6, SC7 and SC18). All three types were produced by Utendoerffer/RWS and both DWM and Egestorff produced two of these types.
The left image I believe is the 12x44R La No6 (SC18) : It can be distinguished from the others by having a smaller c15.6mm rim diameter with a mildly bevelled base. Typically these have a "*" in the hs to make their identification easier.
The right image appears to be the 12.7x44R H (SC6) : This differs from the other two types in that it uses a raised base (some call it a "A" base) that has a slightly thinner overall rim thickness than the flatter based version (SC7) but of the same rim diameter (unlike SC18).
There is also the 12.7x44R F.H. (SC7) which is a Flat based version of the "H" This "FH" was probably the first CF conversion of the 12x44R Norwegian Remington M71 RF cartridge. Like the RF cartridge this has a flat or very mildly bevelled rim and is probably the commonest type of the three.
The compatability of these three cartridge is an open question and can only be answered by actually chambering the cartridges.