You can only really do this by "doubling up" the data source before you
merge, and how you might do that depends on what the data source actually
is. If it's a table in a Word document, you would need to edit the document,
edit|copy the table below the heading row, and edit|Paste to create a single
table double the size. If it's an Access table or query, you can consider
creating a new query that basically does
SELECT 1 AS 'copynumber', * FROM mytable
UNION
SELECT 2 AS 'copynumber', * FROM mytable
ORDER BY 1
Access will probably insist on its own syntax rules.
The problem with this is that if you are relying on a particular sequence of
records, you have to specify the sort order more precisely, e.g. you might
need
SELECT 1 AS 'copynumber', f1, f2, f3, * FROM mytable
UNION
SELECT 2 AS 'copynumber', f1, f2, f3, * FROM mytable
ORDER BY 1, 2, 3, 4
If you are using an ODBC data source such as SQL Server, you can do
something similar in MS Query. If the data source is a text file or an Excel
worksheet, you can do something similar by using MS Query to get data from
the file and specify a UNION query roughly as above.