The phrase 'not one but two novel' could suggest a broader exploration of a certain idea or world. One novel may only scratch the surface, but two can go deeper, covering more aspects, characters, and plotlines. For instance, if it's a science - fiction concept, the first novel could introduce the basic technology or alien species, and the second could show how that technology or species impacts society on a larger scale.
The significance could be in variety. One novel may have a particular style or tone, while the other offers something different. They could target different audiences within the overall readership. For example, one could be more action - packed for those who like fast - paced stories, and the other could be more character - driven for those who enjoy in - depth character studies. Also, it could be a way for the author to show their versatility in writing different types of stories within the same general framework of these two novels.