Service order issue in Repair process

Dear Experts,

I am new to Repair order process but when I used action box for creation of repair order  system is triggering both Repair order and service order at a time and showing system status as  REL-MANC-PRC in the service order.

After changing the Repair order in  VA02 again it's triggering one more service order .

please suggest me where I made a mistake.

Thanks,

Krishna.