Although it looks unusual, the behavior you describe is normal.
When you run an article search, duplicate appearances of the same content are represented as separate items in the first tally of results. As you scroll through the pages, the system constantly removes these duplicates and updates the total number of results. This is an ongoing task that happens while you browse, so the system doesn’t show the final number of results until it finishes "de-duping." Once this process is complete, the last page updates the display with the correct final number of results, which will be smaller than the total displayed on previous pages.
