[BRX]

Even though I've access to a good copy/scan machine which has the feature to scan double pages into single scans I found the best (well relatively speaking) way is to scan the double pages as they are and into one single pdf  (if your scanner doesn't have the option, simply join the scans with one of many available merge tools) and only then split the double pages into single ones with a PDF tool.

The one I found that works quite well for this is "VeryPDF Advanced PDF Page Cut" but there might be others out there (and I'm interested to hear about them in case somebody knows).