Third Party exchange repair type

Hello,

For a third party exchange repair type setup, associated third party ship service activity in the Third Party Ship field and third party RMA field is blank. When i create the repair order with this repair type , see the repair type is created wiht a third party ship line and third party return line. Expectation here is that the repair type will be created with the third party ship line, since in the repair type setup window, only the Third Party Ship line is populated.

Want to know , why this  is happening and how to avoid the creation of return third party line.