It is possible by either using a Directory type mailmerge main document in
which you would only have

<<fname>>

When you execute such a mailmerge to a new document, then you will get

Bill
Mike
etc. for all of the records in the data source

Alternatively, you would need to put a <<Next Record>> before the second
mergefield

<<fname>>
<<Next Record>><<fname>>

But that only works for two records and if you have more than two records,
the next two will appear on the next page.