The file contains pages/scans that should be removed or blanked. (Most likely these are duplicate or suprious pages).
The following pages (DJVU page numbering) should be removed, leaving one scan for each page in the original work: 20,21.
Alternatively to avoid disrupting a work already transcribed, proofread or validated, the pages should be blanked, marked as "Without Text", and the pagelist should be updated to use a "–" or right-arrow "➔" to indicate this for the relevant pages. | 
