SUMMARY
If I try and print two pages from a PDF (a Canon camera manual in this instance), two per A4 sheet, I get four pages, the wrong ones, two per sheet.
The result is the same for larger numbers of pages.
Specifying Print to File causes the pages per sheet option to be greyed out. Also ignores the page number selection and copies the whole file over, but bigger, with each page placed as what looks like A5 in the middle of an A4 page.

STEPS TO REPRODUCE
1. Open a PDF file with okular.

2. Open the print dialog.

3. Open Printer Properties

4. Set Pages per Sheet to 2. OK.

5. Open Options.

6. Select specific pages. (I did not try the Pages From as I needed specific single pages from the file)

7. Print.

OBSERVED RESULT
Four pages are printed, two per sheet. The second of each pair is a page twice the specified page number, the first is the page before.
For instance, if I specify pages 65 and 73, I get pages 129, 130, 145, 146.

EXPECTED RESULT
One sheet containing two pages.

SOFTWARE/OS VERSIONS
Windows: 
MacOS: 
Linux/KDE Plasma: Open SUSE Leap 15
KDE Plasma Version:  plasmashell 5.12.6
KDE Frameworks Version: 5.45.0
Qt Version: 5.9.4

ADDITIONAL INFORMATION

Leap 15 upgraded from 42.3