You could create 2 separate formula fields,
top and
bottom.
In top put something like;
if isnull({table.namefield2}) = true then "" else {table.namefield1}
In bottom;
if isnull({table.namefield2}) = true then {table.namefield1} else {table.namefield2}
In your report place bottom where you'd like the name to display by default and place top above it.
bottom will display the first name if there isn't a second name, and the second name if there is.
top will display nothing is there isn't a second name and the first name if there is.
Regards,
Ryan.