My Rollei reference books are packed away and unavailable, but I recall there were two different sets of Rolleinars.
The earlier set had three pieces, two (thinner) shooting lenses and the (thicker) viewing lens with parallel correction. To use this version, you put one thinner lens behind the thicker lens and mount this on the top lens of your Rollei. The other thinner lens goes on the bottom lens of the camera.
The later set had only two pieces. The viewing and shooting lenses were cemented together as one unit and are mounted on the top lens of the camera.
This is really a sort of kindergarten explanation and I hope it makes sense to you. Rolleinars are a handy tool. They came in four different bayonet sets (I to IV) with three units available in each set. I have the Tessar 3.5 and Planar 3.5 sets and find I use the medium range (2) 90% of the time, the longer (1) 10% and the super close (3) rarely as it puts me too close to things I prefer to stay away from, like angry bees on flowers. The II is ideal for most close-ups, the I is useful for cat portraits and the like.
Both your thinner lenses should have the same number (2). If not, they are mismatched.