Trivial SSCCE:

#!/usr/bin/env perl 
use strict;
use warnings;
use HTML::Template;

my @sources = (
    "Hello <TMPL_VAR NAME=FOO>\n",
    "Goodbye <TMPL_VAR NAME=FOO>\n",
);
my @templates;

# Create and populate 2 templates with one loop
for my $source (@sources) {
    my $tmpl = HTML::Template->new (scalarref => \$source);
    $tmpl->param (FOO => 'StrangeDucks');
    push @templates, $tmpl;
}

# Output from the two teamplates
for my $t (@templates) { print $t->output }
[download]

See also the HTML::Template Tutorial.

(Edit: minor update to improve generality.)