use Data::Dump qw/ dd /;
use CGI;
my $q = CGI->new('ro=row;ro=you;bo=boat;bo=diddly');
my %in =  map { $_ => [ $q->param($_) ] } $q->param ;
dd( \%in );
__END__
{ bo => ["boat", "diddly"], ro => ["row", "you"] }