Go to the Tools ... Developers Tool Kit ... and in the bottom input box enter:
multiple_product_copy_return

and select Admin and Click SEARCH ...

Do you get:
/home/yourusername/public_html/yourdirectory/yoursecretadmin/includes/modules/copy_to_confirm.php

Line #150 : if ($action != 'multiple_product_copy_return') {

/home/yourusername/public_html/yourdirectory/yoursecretadmin/includes/modules/move_product_confirm.php

Line #42 : if ($action != 'multiple_product_copy_return') {

/home/yourusername/public_html/yourdirectory/yoursecretadmin/includes/modules/product_music/copy_to_confirm.php

Line #173 : if ($action != 'multiple_product_copy_return') {

/home/yourusername/public_html/yourdirectory/yoursecretadmin/multi_product_copy.php

Line #140 : $action = 'multiple_product_copy_return';

Line #224 : $action = 'multiple_product_copy_return';

Line #272 : $action = 'multiple_product_copy_return';