It doesn't matter if they were ever on the tables or not. They were ordered by and delivered to the casino, They are real chips.
How can anyone say with certainty (is that a word?) they were never on the tables. The casino was open 3 years. Odds against at least one $25 BJ player hitting a good run in 3 years are probably as big as your 2 in a row royal flush odds.

BTW, I only know of 2 times the $500's were on the tables the 5 years I worked at the Fiesta. There could have been others, I am not aware of, but it was not the norm.