I suppose that you mean a close up Rolleinar for a TLR since you mention "Heidosmat" which is the finder lens of the TLR. This is always a set of two Rolleinars. In the upper one there is a glass wedge for compensating the parallax between the two lenses (the so called "Rolleipar Keil"). This wedge has to be inserted in correct orientation, otherwise you'll have a finder picture different to that on the film. The second lens has no wedge and is for the taking lens.