Concurrent left and right hand circuits are not that uncommon at uncontrolled aerodromes in the UK. Gliders one way, power another with microlights inside the larger power circuit at lower circuit height. And as for the the helicopters... This is usually stated in the published aerodrome information.
As an aside rule of the air 14 states:
(2) Subject to paragraph (5), a flying machine or glider shall not land on a runway at an aerodrome if there are other aircraft on the runway.
(5) Paragraphs (2) and (4) shall not apply if the air traffic control unit at the aerodrome otherwise authorises the flying machine or glider.
When two gliders are on final to an uncontrolled runway, and the first lands, what is the second glider supposed to do?
P.S My favourite instruction from ATC after having received multiple heading changes to get me thoroughly lost when flying VFR in class D airspace is to be told 'resume own navigation'.