Can not declare class Helpers

An error occurred when entering the page of the material editing form - on the white page the message:

Fatal error: Cannot declare class OrdersHelpersOrders, because the name is already in use in
.......\administrator\components\com_orders\helpers\orders.php on line 18

code:If you change the directory name
..........\administrator\components\com_orders\helpers+++\
page editing form appears.

What is the problem?

This service works with Joomla 3.7?

Thank you.
Everything works perfectly!