You don't have to be on Windows to be bitten by this browser mismanagement.
Iceweasel on Debian wheezy and Firefox on Ubuntu-12.04LTS also throw in the extra 10 bytes when downloading Text-CSV_XS-1.01.tgz from CPAN.
(Sorry - I don't know the version numbers of those 2 browsers - and couldn't quickly find out how to get them.)