title: Reading qrcode (non-unique) once per session with Arkit+Vision
body: <p>Given two <code>QRcode</code> (not unique) fixed in space.
  As with <code>Arkit</code> and Vision, count each code once per session, even if we take away the camera.</p>
  
  <p>I managed to write reading <code>QRcodes</code> into a session (hitTest) and using Vision to recognize and add a 3D object, but how to read two (or more) identical barcodes on the screen once (even if we remove the camera and return the <code>QRcodes</code> to the same)?
  Can  remember them  coordinates?</p>
  
  <p>Please tell me please</p>