Welp. that's an MX alright. Body, at least. The small focus knob, the short lever above the flash sync socket, the style of the strap lugs, etc.
And yep, it says Planar.
I don't know exactly what to look for, but there are ways to tell how many elements are in a lens by the ways that reflections happen, the number, etc. Maybe someone can tell you.
The interesting thing for me is that a 3.5 Planar or Xenotar lens does fit a #00 shutter. And the front lens element is very close to the size of a Tessar/Xenar front element. On the 3.5 Es and Fs, the Bay II fitting was some sort of marketing BS move by Rollei, not a neccessary change because of the new lenses. If you look at a 3.5 E or F, you will see an extra black ring outside of the lens element filling in the extra space for the Bay II mount rather than a Bay I mount. There might need to be some widening, but a Planar will fit a Bay I camera. Some day I will mount a Planar onto a Minolta Autocord body with a Hasselblad NC-2 prism and I will have my perfect camera.
Anyway, either someone swapped the front ID plate on the lens, or you have a franken-rollei.
A note and photo to Harry Fleenor might be in order. I seriously doubt that this a collector item worth lots more than $250. More a curiosity piece worth whatever pleasure you get from shooting with it.
By the way, it is not recommended to go to 1/500 second with a cocked shutter on this early Synchro-Compur. These shutters still used a tensioning spring booster for 1/500, and trying to engage that with a cocked shutter is extremely difficult and can damage the shutter.