well line 55 of image-inc.php has not changed in many many versions nor has the function
$check = move_uploaded_file($tmpname, $dst_file);
As far as uploading files of the same name you not suppose to be have the images the same name on the 6 boxes on upload.
Now the bulkupload code already has the ability to rename images but its just for one cat. So this should solve the issue of moving images.
In uploadproduct.php delete this
Content visible to verified customers only.
Then the script should rename any files you upload.