Hm, I cannot reproduce the issue:

#!/usr/bin/perl -w
use strict;

while (<DATA>) {
    chomp;
    push @::Lines, $_;
}

for my $machine (qw(machine1 machine11 machine12
                    machine2 machine20 machine23 machine30)) {
    for my $line (sort @::Lines) {
        if ($line =~ m/\Q$machine\E\b/){
            print "$machine : $line\n";
        
        }
    }
}

__DATA__
\\hostname\Cpu(123:machine1)\%Ready
\\hostname\Cpu(3545:machine11)\%Used
\\hostname\Memory(3244:machine30 (ef0a-14f09a-dfe230d-ea5f8d))\Swapped
+ MBytes
[download]

Output (as expected):

machine1 : \\hostname\Cpu(123:machine1)\%Ready
machine11 : \\hostname\Cpu(3545:machine11)\%Used
machine30 : \\hostname\Memory(3244:machine30 (ef0a-14f09a-dfe230d-ea5f
+8d))\Swapped MBytes
[download]

Update: sorry, misread your post... (quotes with "machine30 (ef0a-14f09a-dfe230d-ea5f8d)" would've made it clearer — which only goes to show that a piece of runnable code is often better than prose).