I'm assuming that you created an InDesign file as your template, your original notepad is 5.5" W x 8.5" H and that you want to print 2 pages per US Letter sheet?
If so, you can create a new document that is 11 W x 8.5 H (uncheck facing pages) and use the Place command to place the original InDesign file into the new document. Then duplicate the placed content so they are sitting side-by-side.
If this is for printing multiple pages quickly (i.e. 10 pages of 20 sheets or so), then you can also cut those 2 placed copies and paste them into your A-Master page. Then just create as many new (non master) pages as you need. Then when you update the original indesign (or other source) file all the pages in the new layout would update.