Several strange 1968 Kiev 4 and 4a appeared recently: they don't wear the usual logo on the clip, only the serial number. There is nothing else different compared to the running production.
For the moment, we don't know why. Several hypothesis are evoked in the related thread here: https://ussrphoto.com/Forum/topic.asp?TOPIC_ID=3693
Known serial numbers:
Type------Serial number-------Lens s/n--------------Owner/origin
4a_______6806307___________Jup 8M 6821801_____seen on the net
4a_______6811264_____________________________Alexander K.
4________6816332___________Jup 8M 6824327_____Jacques M.
4________6816711___________Jup 12 7804048_____Jacques M.
4________6817037_____________________________Alexander K.