There are peculiarities. It is theoretically possible but takes too much efforts to be practical. And it would make a highly punishable offence to risk it.
Let’s see: you have ten pounds of beef that measure at 1600 counts per minute (cpm) but allowable radiation level is 50 cpm, a little above background. So you grind up that ten pounds with 400 pounds of uncontaminated meat, and end up with 410 pounds of hamburger that measures below background.
From the radiation standpoint, this does not place anyone in danger. From the heavy metals standpoint, this may or may not be a problem; there is not enough evidence to make a determination. Regardless, it is highly unethical to take such action.
In any case, I would not expect Soviet officials would have been punished for doing such a thing. My impression was that the Soviet political class could get away with a lot.