I have 1989 Polish Meat Ration card that I keep on my refrigerator. It has a serial number, year-month indicator, a unique watermark, and several other anti-counterfeiting features. This ration card would have been validated with a simple rubber ink stamp, or unique shape punch stamp. Of course when you control the means of production, you can tightly control who gets the both cards and the stamps. Hint - they would not be the same person or group.

If you've ever checked out of a Soviet-era grocery store, you know that you bring the items you want to buy to one counter, then they ring it up and give you a receipt. You take the receipt to another counter to pay. Then you take the validated receipt back to the first counter to pick up your groceries to carry home. Something similar would happen when you picked up your ration card as you would need to get it stamped to validate it's authenticity and then different stamp would be used when each allotment of food, in this case meat, was apportioned to you.