Your string as described ends with a colon. All you need is chop - no need for regex:

use strict;
use warnings;

use Test::More tests => 1;

my $have = 'a:b:';
my $want = 'a:b';

chop $have;

is $have, $want;

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In reply to Re: Breaking symmetry with a regex by hippo
in thread Breaking symmetry with a regex by Anonymous Monk

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