When adding or editing a form with 2 or more file upload elements only the first one is uploaded, no matter wich of all upload button you press.
This happen when the form generate a duplicate uniqueid for inputs and buttons that are involved in selecting and uploading a file.
The problem is that library Grocery_CRUD.php,v1.3,function get_upload_file_input,about line 2531, try to generate a uniqueid
$unique = uniqid()
But, according to this post: http://stackoverflow.com/a/4070285 it sometimes happen that 2 or more uniqueid are generated in same second(windows) or microsecond(unix), and this causes the failure with the upload file buttons.
In my case I just changed line $unique = uniqid() by $unique = rand(10,9999) and problems with file upload dissapear...
I suggest using something else than uniqid() to avoid this kind of problems...