As mentioned in the mailing list by Martin, i open this as a bug...
Its not possible to use 303 as redirect (SC_SEE_OTHER) because thats not supported, only 302 and 301 are supported but this is defined in RFC HTTP 1.1 from 1997.
301 will add the Location header - which works as expected when disabling cookies. But a 302 (which is what i prefer) will redirect to the same page because the Location header is missing. When i enable cookies, its working.
Example can be found here: https://github.com/olze/WicketRedirect