I just tried it too. It turns out that import_names() does this in an interesting fashion; it imports all parameters as both scalars and arrays.

#!/usr/local/bin/perl
 
use CGI;
 
my $query = new CGI ( { single => 'one',
                        multi  => ['two', 'three'],
                      }
                    );
 
$query->import_names('Q');
 
1;
[download]

Now, using the debugger to examine the results:

Loading DB routines from perl5db.pl version 1.0402
Emacs support available.
 
Enter h or `h h' for help.
 
main::(tmp.cgi:5):      my $query = new CGI ( { single => 'one',
main::(tmp.cgi:6):                              multi  => ['two', 'thr
+ee'],
  DB<1> n
main::(tmp.cgi:10):     $query->import_names('Q');
  DB<1> n
main::(tmp.cgi:12):     1;
  DB<1> V Q
$single = 'one'
@single = (
   0  'one'
)
$multi = 'two'
@multi = (
   0  'two'
   1  'three'
)
  DB<2>
[download]