Are you allowed to overtake vehicles on other lanes at a junction marked in such a way?

Yes, overtaking at a junction with a circulatory system, a so-called roundabout, is permitted. According to the regulations, this is one of the exceptions to the general rule prohibiting overtaking at junctions. As stated in Art. 24 para. 7 pt. 3 of the Road Traffic Act, this manoeuvre is permitted at a roundabout or at a junction where traffic is directed.