I have the same problem converting a double page scan to two single pages times 70+.
Investigating, the best means I have found so far is called A-PDF Page Cut at
www.a-pdf.com/page-cut/index.htm, which gives a good pictorial description of it's function. (98/NT4/Me/2000/XP/Vista) Being shareware, you can try it for free, or purchase for $27.
Seems to be very simple to use and very quick. At last a solution to my problem!
https://www.mobileread.com/forums/ima...1/thumbsup.gif
(BTW I am not connected to the s/w in any way!)