You can try this straight-forward solution:

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

# Define patterns to look for, and create a regexp with them.
my @patterns = qw(1dlw 1sdh 1cgi 1xnf);
my $expr = join("|", map {quotemeta} @patterns);

# The source array.
my @source = (
    '$?/1dlw&', '*%1sdh^?', '@/!1dlw\/',
    '$£1cgi*&', '?@1sdh%&', '~#1xnf$%',
);

# Iterate over each element in source,
# and store how many times each pattern
# is found.
my %seen;
foreach my $element (@source) {
    if($element =~ /($expr)/) {
        $seen{$1}++;
    }
}
# ...and remove the patterns found more than once.
while(my($pattern, $count) = each %seen) {
    @source = grep {!/\Q$pattern\E/} @source
        if $count > 1;
}

print join("\n", @source), "\n";
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