Dublicated Navigation

Hello, I’m using the latest version of BPGE and I have a problem. I created I site like discripted in the tutorial.

But now the navigation für these sites ist dublicated. Two rows are being created.

It seems to be the same problem like in this post: http://ww.wp.xz.cn/support/topic/duplicate-navigation-and-no-formatting?replies=5

Can u help me? I’m using the theme “Twenty Thirteen”

http://ww.wp.xz.cn/plugins/buddypress-groups-extras/