There are several ways to do this (some may not be available in older
versions):
1. You can use the "2 pages per sheet" option in the Print dialog. This,
however, will reduce a full page to half a page, so it is not suitable for
half-page documents.
2. You can use columns (for vertical half pages) and just copy/paste the
content from the first column into the second, inserting a column break if
necessary; make the space between the columns equal to the sum of your left
and right margins. But I suspect that your "half page" is the top half of a
portrait sheet rather than the left half of a landscape sheet.
3. For horizontal half pages, you can again use copy/paste; you'll need to
adjust the spacing between the copies to be equal to the sum of the top and
bottom margins. Alternatively, you can set up a single-column borderless
table with exact row heights. Although you can do this with a two-row table,
it's easier with three. Make the height of the (empty) middle row equal to
the sum of the top and bottom margins.
4. If you have Word 2000 or above, much the simplest way to accomplish this
is to use the "2 pages per sheet" option in Page Setup. This can be arranged
either horizontally (on a portrait page) or vertically (on a landscape
page). You still have to copy/paste the contents onto the second "page," but
everything else is handled for you automatically.
