anyone done this before?

I put a sell order on through Commsec yesterday and hit the wrong button (am a new Commsec client). As I had funds available a buy order (not sell order) went through ...I now have twice the holding (which is a large holding) in a stock as I did before. First time I've stuffed an order up in 8 years.

Teach me for trying to juggle phone calls from clients and internet trades.