The early CERTUS history is a real enigma. Seems to have been introduced in 1890 and then certainly updated to the "New Model" that was patented in 1900.
My (un)educated guess is that the "New Model" was designed to handle the Cordite cartridges that would not have been around in 1890 and the only CERTUS documentation that I find is of the post 1900 "New Model".

As to those pictures, the top one is almost certainly the "New Model" with the safety lever, long receiver slide, pistol grip stock, and barely visible "bush safety" ahead of the bolt handle.
The bottom picture? Most likely one of the original 1890's versions and maybe a single shot? The military style ladder sight and 33" barrel with Metford rifling are interesting.
- Mike