I upgraded to Designer Pro X 19 from 17. Using 19, when I export my design to an HTML web site it is duplicating version of many of the HTML pages. I did not have this issue with 17 or earlier versions of Designer Pro X. For example, exporting index.html results in index.html, index 2.html, index 3.html, etc...
Here is the list of pages in Xara, and a screenshot of the output directory the HTML pages are written to. Notice the "2" after most of the pages. If I export again, the next copy will be "3", then "4", etc...