You could use something like this...

#!/usr/bin/perl -w
use strict;
use POSIX qw|strftime|;

my $time = strftime('%I:%M:%S %p', localtime(time() - 60 * 60 * 2));
print "$time\n";
[download]

Update: You didn't specify if the time was ahead or behind 2 hours. Just use time() + 60 * 60 * 2 if it's ahead.

Joshua