...
if ($cmp eq $clt)
{
    print "correct!\n";
}
else
{   use Data::Dumper;
    $Data::Dumper::Useqq=1;
    print Dumper(\$cmp,\$clt);
    
}

# Output:
$VAR1 = \"u_ser_a";
$VAR2 = \"u_ser_a\0";