Actually you can submit more than 1 application.
If you can afford the cost of sending 2 applications then by all means send another one. If the first one is rejected due to the missing visa office field there is a chance the 2nd one could be accepted. But be warned I think you will be on very tight timelines with the 2nd application.
I'd add an explanatory note saying that you are sending this 2nd application because you believe you missed a field on the first application. Once the completeness checks are done, if by any chance both applications make it through than the officer doing the eligibility review may be able to marry the 2 applications up and will ask you which one you want to cancel.
Be aware this will involved a second lot of processing fees though, as well as getting all the necessary supporting documents together (originals where required such as IELTS results).
I can absolutely guarantee they won't deny the first application just because they've received a second, each one will be judged on its merits, so it's a no-lose situation from that point of view if you can afford the costs involved with the 2nd application.
Wayne.