Maybe something like this:

use strict;
use warnings;
use Text::Autoformat;

my $text = do { local $/; <>; };
my $formatted = autoformat $text, { 
    left    => 1,
    right   => 38,
    justify => 'full',
    all     => 1
};

my @lines = split /\n/, $formatted;
if ( @lines > 50 ) {
    my $lines = int( ( @lines + 1 ) / 2 );
    $formatted = '';
    for ( 0 .. $lines - 1 ) {
        $formatted .= sprintf "%-38s    %-38s\n", $lines[$_],
            ( $lines[ $_ + $lines ] ? $lines[ $_ + $lines ] : '' );
    }
}

print $formatted;
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