Availability check issue

Hai Gurus

I have a scenario in hand. we got two orders for 50 quantities. We got total stock of 50. I have created sales order 1 with 50 quantities. Later I have created sales order 2 with 50 quanties. Now Sales order 2 has to be delivered first. When I tried to deliver, the system is showing no shedule lines as 50 quanity have got confirmed for sales order 1. Now what I have to do is to go and change the quanitity in sales order 1 to 0 quanitity as then only sales order 2 can be delivered. Could you please advice me to give an alternate solution so that I can deliver sales order 2 wihtout changing quantity from sales order 1.

Regards

Sidhu