Maybe you should look at Tk::Radiobutton, which will allow you to allocate a set of buttons so that only one button may be selected at a time. The example below is an abbreviation of the example included on page 84 of O'Reilly's Mastering Perl/Tk:

$group1 = 100;
for (qw/1 10 100 1000/) {
    $mw->Radiobutton(
        -text => $_,
        -variable => \$group1,
        -value => $_,
    )->pack(
        -side => 'left',
    );
}
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