Having 2 file uploads should give you 2 entries in the HTTP_POST_FILES array that you can use to access the temporary files that were uploaded. In theory, the following should work.
copy(HTTP_POST_FILES['file1']['tmp_name'], $destdir."/".HTTP_POST_FILES['file1']['name']);
copy(HTTP_POST_FILES['file2']['tmp_name'], $destdir."/".HTTP_POST_FILES['file2']['name']);