Why not place each page in a Tk::Frame, then use packForget to remove the current one from the main window then pack a new one? Sort of like Java's CardLayout:

use Tk;

$mw = MainWindow->new;

$page[0] = $mw->Frame();
$page[1] = $mw->Frame();

$page[0]->Button( -command => sub { setpage(1) }, -text => 'Go Page 2!
+' )->pack();
$page[1]->Button( -command => sub { setpage(0) }, -text => 'Back to 1'
+ )->pack();

$page[0]->pack();

$curpage = 0;

MainLoop;

sub setpage {
    my $n = shift;
    $page[$curpage]->packForget();
    $page[$n]->pack();
    $curpage = $n;
}
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