#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11118320
use warnings;
use Tk;

{ # for package
package Tk::ListBox3;

use List::Util qw( first );
use base qw/ Tk::Frame /;     # Frame-based composite
Construct Tk::Widget 'ListBox3'; # install MyNewWidget in pTk namespac
+e

sub ClassInit                  # called once to initialize new class
  {
  my($class, $mw) = @_;
  $class->SUPER::ClassInit($mw);
  }

sub Populate                # called to build each widget instance
  {
  my($self, $args) = @_;
  $self->SUPER::Populate($args);
  my $search = '';

  my $frame = $self->Frame(
    -borderwidth => 5, -relief => 'ridge',
    )->pack(-fill=> 'both', -expand=> 1);
  my $label = $frame->Label( -fg => 'blue', -font => 30,
    )->pack(-fill => 'x');
  my $lbox = $frame->Scrolled(Listbox => -scrollbars => 'se',
    -height => 20,
    -selectforeground => 'orange',
    -selectbackground => 'steelblue4',
    -exportselection => 0,
    )->pack(-side => 'bottom', -fill => 'both', -expand=> 1);
  my $entry = $frame->Entry(-textvariable => \$search,
    -validate => 'key', -validatecommand => sub
      {
      my ($want) = @_;
      length $want or return 1;
      my @list = $lbox->get(0 , "end");
      my $item = first { $list[$_] =~ /^\Q$want\E/ } 0 .. $#list;
      defined $item or return 0;
      $lbox->selectionClear( 0 , "end"  );
      $lbox->selectionSet($item);
      $lbox->see($item);
      1 # to allow
      },
    )->pack(-fill => 'x');

  $self->ConfigSpecs( DEFAULT => [$lbox], text => [$label] );

  $self->Delegates( Construct => $lbox, insert => $lbox );
  }
} # end package


my @choices = sort qw /alpha beta charlie delta echo foxtrot hotel ind
+ia juliet
  kilo lima motel nancy oscar papa quebec radio sierra tango uniform v
+ictor
  whiskey xray yankee zulu oin gloin beorn gandalf elr ond eowyn/;
my $header_msg = "ENTER a KEY name: ";

my $mw = MainWindow->new;
$mw->geometry( '+900+250' );
$mw->title( 'Listbox' );

my $lb = $mw->ListBox3( -text => $header_msg,
  )->pack(-fill => 'both', -expand => 1, -side => 'left');
$lb->insert( 'end', @choices );

my $lb2 = $mw->ListBox3( -text => $header_msg,
  )->pack(-fill => 'both', -expand => 1, -side => 'left');
$lb2->insert( 'end', @choices );

MainLoop;
[download]

Demos two of them to show no interference.