I scan contracts using Adobe. But when the pages scan, it only shows one side of the page.

Whenever you scan a "new" document, it's important to run the "Prescan" in the scanner's software. This shows you what the scanner is set up to scan AND lets you fine-tune the settings so that you get a good quality scan. (Think of the gray page with the text on the opposite side bleeding through the page your scanning.)

When you do the Prescan, look to see that the margins are encompasing the document you want to scan, the light grays are now white, the blacks are a good black and you should be good. There is no reason to use the Prescan for subsequent pages as long as they are no different from the first page. If every page is different, than yes, you do have to do the Prescan for each page.