Use a catalog, or in Word XP and later it is called a directory, type
mailmerge main document in which you have only a one row table, in the cells
of which you insert the merge fields.  When you execute such a merge to a
new document, that document will contain a table with a row of data for each
record in the datasource.

If you mean that you want the data arranged in two columns, format the main
document to have two columns and setup the table in the first column.