There is no preceding form factor that LPCAMM2 will replace. It's the first standardized removable module for LPDDR. Prior to this, LPDDR has only been usable in soldered-down packages.
Emphasis on 'standardized' -- the 2 in LPCAMM2 is indeed meant to refer to the second generation of LPCAMM, but it's the first generation that has been approved as a JEDEC standard (and therefore, the first one that most people will be able to buy).
Was the original CAMM from Dell ever used with LPDDR, or just DDR5?