I have a flatbed scanner (part of my printer). I had no idea it was possible to scan a multipage document in Xsane. For a pull-through, sure, maybe, those can go through a stack of pages on their own. But a flatbed? Every time I've tried this before, I scanned individual pages, saved them as images, put them into an Open Office Writer document with one image per page, then saved that as a PDF. There's a better way!
So here's what you do. In the XSane window where you choose color/greyscale, gamma, brightness, etc, at the top there's a dropdown that defaults to Viewer. Change that to Multipage. A new window will open called "xsane multipage project." Choose the "New Project" button. Back to that first window, hit the Scan button. The scanner will do its part, and a page will be listed in the project window. Swap in a new sheet of paper and hit the Scan button again. Repeat until you've scanned all you need. If you scanned them out of order, use the arrow buttons on the project window to rearrange them. You can also delete any pages you don't need. The Show Image button lets you preview an individual page. The default output format is PDF, so just click the "Save multipage file" button at the bottom of the Project window when you're done.
This makes things so much easier.