In September 2018 Ebay seller 1minabox2013 from Simi Valley, California was trying to sell these movie prop plates. He is selling them as movie prop plates and he has well over 100 all told. They are made of plastic not metal.
Most of them are fairly close to the real plates design wise but the big problem will be if some of the cheats/liars/thieves on Ebay buy them to resell as genuine used plates with some fancy story about why they are not metal.
ALWAYS check with someone or some group or some website if the item for sale is even possibly a real genuine, used number plate.