Description:
------------
My enviroment is php5.3.1+IIS5.1+FastCGI. I execute the following code and get two files: test.zip.a00564 and test.zip.b00564. Again I execute it and get two new files: test.zip.c00564 and test.zip.d00564.  After a moment to carry out it again, the end of the serial number of the file's name is change as 01892, such that the two files' names are test.zip.a01892 and test.zip.b01892.

Test script:
---------------
<?php
$zip = new ZipArchive;
$res = $zip->open('test.zip', ZipArchive::CREATE);
if ($res === TRUE) {
    $zip->addFromString('test.txt', 'file content goes here');
    $zip->addFile('data.txt', 'entryname.txt');
    if ($zip->close()===TRUE)
       echo 'Yes';
    else  
       echo 'No';
} else {
    echo 'failed';
}
?> 

Expected result:
----------------
Yes
Generate the archive test.zip

Actual result:
--------------
No
Generate two files: test.zip.a00564 and test.zip.b00564