How is your mail merge main document set up?

My guess is that you have set  a <<Next record>> field followed by the
fields you want for each client, repeated a number of times down the page.
Because Word always moves to a new record automatically when it starts a new
copy of the mail merge main document, you don't need a <<Next record>>
before the /first/ record. But in any case, if my guess is correct, you
probably need to redesign the merge as a "Directory" merge and only have
/one/ copy of those client fields, and no <<Next record>> fields at all.

Peter Jamieson