Renames each of the @var{count} variables in @var{vars} to the name in
the corresponding position of @var{new_names}. If the renaming would
result in a duplicate variable name, returns false and stores one of
-the names that would be be duplicated into @code{*@var{err_name}}, if
+the names that would be duplicated into @code{*@var{err_name}}, if
@var{err_name} is non-null. Otherwise, the renaming is successful,
and true is returned.
@end deftypefun