Debian 8.1 AMD64, Brother MFC-7860DW printer. Duplex printing works except when I request multiple copies. A 2 page document - when printing 3 copies occupies 3 sheets as expected, BUT all copies of page 1 are printed on the first 3 sides and page 2 occupies the next 3 sides! It seems to be LO problem as it happens in Writer and Calc, but does not happen for Scribus. Work-around: export to PDF and print from that. It is not a problem when printing to the same printer from LO 4.2.8.2 in Ubuntu x86.
Have you tested how it behaves with LibreOffice 5.x? https://wiki.documentfoundation.org/Installing_in_parallel/Linux Brother is known to be problematic, lots of different bug reports.
Also, is this the same as Bug 96180? Simple search for: Brother duplex.
Let's set to NEEDINFO, while we wait for comments from Bruce. Set to NEEDINFO. Change back to UNCONFIRMED, if you think it is different from bug 96180. Change to RESOLVED DUPLICATE of bug 96180 otherwise.
Apparently not the same as 96180; page appearance was fine. My problem was in printing multiple copies of duplex document. Instead of: p1,p2 p1,p2 p1,p2 I got: p1,p1 p1,p2 p2,p2 OK, I got 3 copies of each page, but not organised the way I wanted! :-) There was one sheet with both pages ... I have been away, so have not yet tried a parallel install to check the behaviour of LO 5.
Seems as though LO 4.3 might be the problem. I have now done a parallel install of LO 5.0.4 and used it to print the document. Perfect! 3 sheets printed, p1 & p2 on each (i.e. p1,p2 p1,p2 p1,p2). Works for me!
Great to hear! If you would sometimes like to help with bugs: https://wiki.documentfoundation.org/QA/Triage_For_Beginners