Ok, good starting point, thanks so far! However, I think (also because of duplicate content) this approach is not the best. After a bit of research I found the perfect solution.
Using a simple hook does the trick:
http://processwire.com/talk/topic/1799-routes-and-rewriting-urls/?p=16708
wire()->addHookAfter('Page::path', null, function(HookEvent $event) {
$page = $event->object;
if ($page->template == 'account-profile') {
$event->return = '/'.$page->name.'/';
}
});
Anyway, thanks for the fast support and explanation!
Cheers,
Yannick