(in 2.6.1) Gzipping twice

[ line 519/586 (88%), col 13/53 (24%), char 19406/21735
(89%) ]

changed:
$dump_buffer = gzencode($dump_buffer);
to:
//$dump_buffer = gzencode($dump_buffer);

Is the server gzipping the $dump_buffer twice? I used
my hex editor to remove '15' additional bytes at the
header/beginning of the file it outputs, finding that,
afterwards, the gzip file was only then useful. Any
ideas why this is happening?

Paul