Goofs, as any other information on this site, gets filtered by the appropriate IMDb team. However there might be some mistakes or repetitions. That's a reason why the contributors' zone is important.
You can correct inaccurate information, or in your case delete a goof that is listed twice, by following some simple steps. Firstly press the edit button which is at the bottom of the film page. Then you can find goofs in the fun staff section. So next to the goofs there is a box where you should choose correct/delete. I guess the next steps are pretty clear but if you find trouble in something don't hesitate to ask.
I hope that this reply will be helpful.