Are you sure that there were 2 orders at the same time? It could be bug in the expert, but I'm doubt there's any, since the code base has been used for months without problem. There's a possibility that you attached the EA to multiple charts of same currency pair.
If you're talking about the delay, I've implemented Smart Delay in the EA. Before an order is executed, the EA checks if MT4 is available to execute or not. Order is executed according to MT4 state. If it's busy, wait. If it's not busy, don't wait. Smart Delay is more decent than that shown at mql4.com which uses very classic, fixed-interval, always delay.