How to draw double gridline between columns in tables?

[Reinaldo]

Actually, we would like to have tables split side-by-side, say, two tables
(one at the left, one at the right), but we'd be happy just to draw double
gridline between columns; it may achieve the same purpose.

 

[Suzanne S. Barnhill]

See http://word.mvps.org/FAQs/TblsFldsFms/Borders.htm

 

[Reinaldo]

Thanks Suzanne. Since this is a long article, I don't have the time to read
it entirely yet, much less give it a try, but there is always time to thank
you; regards, Reinaldo

 

[Suzanne S. Barnhill]

The key clue is that you must select a border style *before* applying it.
Once you figure this out, it seems logical, but I can't tell you how many
times I've selected a border in the "preview," then changed the line style,
and found that nothing happened. Change the line style and *then* click on
the preview, and it works as expected.