Look on your computer John, you probably already have software that will do it, because you have a scanner.

Some you can COPY an image, or CUT a front that you want, close the original (don't save the one you cut from) and open a NEW image, then Paste to it.

Copy the back side scan, and open the above new_image paste.

Some software will allow you to open multiple images, so you can easily copy and paste without all the open and closing.

Also some have the Redimension command which lets you make an original image size larger, but doesn't change the image portion of it. For example you have a chip scan that's 90 x 90 and you want to add the other side. You redimension it to 90 x 180 and you will create a blank space for the other side of the chip.

I prefer the Lview software, which does just about everything I need to do, without having a couple of megabytes of extra features, that I'll never use.

I have Photoshop (various people make the same name software) Photo Studio, Corel, Kodak (comes free with many scanners) and there are many others like Matese or Ulead that were included with scanners, cameras, and interface cards.

That chances of you not already having at least two pieces of software that will do the trick, are very slim. Windows comes with one as well...