I think you might better do so with a pattern-matching, e.g.

my @result = $string =~ /^([^\.]\.[^\.])(:?\.([^\.]))*$/;
[download]

or something the like.

Or use split and some after-working:

my ($firstPart, @result) = split(/\./, $string);
$result[0] = $firstPart . "." . $result[0];
[download]

Best regards,
perl -le "s==*F=e=>y~\*martinF~stronat~=>s~[^\w]~~g=>chop,print"