Ahhhhh.
The system should not have allowed you to submit an update to a skin already in the update queue. Unless you used the browser back button and hit it there. All bets are off in that case, but it would account for the error as that is the other place I can catch someone trying to update a skin which has already been submitted as an update.
I refuse to put Java code into this as that opens another can of worms.
No, the amount of problems in allowing an update to be updated before it is reviewed are quite numerous. The single biggest one being there would be no way to insure the file actual got sent down. That is already tough enough.
If you are using the browser back and forward buttons, then you are not using the site the way it was intended to be used. I have made an effort to catch that, but there will be residual side effects, based on which browser you are using and I cannot control those.