just do ONE declaration in the surrounding scope!

      my $which_radio_button = param('P1P2_bugs');
 
      my $rec_type;
      my $y_label;
        #
        #Decide the rec_type based on the Radio button selection
        if ( $which_radio_button eq 'P1' ) {
            $rec_type = '3';
            $y_label  = 'Open P1 Bugs';
        }
        elsif ( $which_radio_button eq 'P2' ) {
            $rec_type = '4';
            $y_label  = 'Open P2 Bugs';
        }
        elsif ( $which_radio_button eq 'P1-P2' ) {
            $rec_type = '2';
            $y_label  = 'Open P1-P2 Bugs';
        }
        elsif ( $which_radio_button eq 'Daily-Snapshot' ) {
            $rec_type = '1';
            $y_label  = 'Daily-Snapshot';
        }
[download]

should do!