Everyone on this site has been sucked into a drop dead gorgeous coin that we paid to much for… Don’t give it a second thought. It’s the price of admission.
IMHO this is an impaired proof. Lighting is definitely making it difficult to know for sure. There appear to be some circulation marks. The devices/letters of EPU being well defined and "thin" are the best indicators for me. EDIT: I forgot to add that there also appears to be some frosting on the letters on the reverse. Thank you for this link. I was aware of the two re-engraved dies for 1953 but not this one for 1950. There is a second proof variety DDR-001 but this coin doesn't exhibit any Class 6 thickness on the reverse devices that I can see. http://varietyvista.com/01a LC Doubled Dies Vol 1/1950PDDR001.htm