@kornboi Thats just how it was published. Choosing to combine the two or leave them separate them are up to the scanlators. FWIW, when there are repeat pages like this, sometimes a few subtle changes are made to the art or text. Though, I believe this manga doesn't do that.
But, more importantly, Mangadex "missing chapter" feature is currently capable of dealing with partial chapter releases and full releases, but hiccups when they are intermixed. If we had ch14 and then ch15.1 was uploaded tomorrow, the reader would detect that as a missing ch15. (and the reader would give a warning page in-between the chapters) Only a minor nuisance, but when every other chapter is a full release, it quickly gets annoying.
For that reason, I would personally rather they stay consistent like this even if they have a full chapter to upload.