After the first double sided page, individual pages are flipped/reversed ordered in the output e.g. 1,2,4,3,6,5,8,7,10,9,....
When using a double sided scanner, XSane seems to process the pages in correct order. Simple-scan for v3.28.1-2, v3.30.0-1 flip the pages when scanning >1 double sided page. i.e. page order for double sided pages becomes 1,2,4,3,6,5,8,7,10,9,.... Scanner: AVISION Sheetfeed Scanner AV220D2+ simple-scan.log OS: Archlinux XSane: v 0.999