Foreign tokens were sorted from daily drops.
Most casinos subscribe to a service that runs foreign tokens and chips back to the issuing casinos for a % of total. Some do it every 2 weeks and some once a month.

James is correct about the signs. Using foreign tokens was discouraged.
Per gaming regs, casinos can not cash foreign tokens and chips for customers. They can only change them out for their own. If you bet a foreign chip, dealer should change it and drop the foreign chip.

Back in the days, I have seen 100's of slugs in slot drops.

Good slot story I have told before. Not about tokens but funny.
In 1981 I was waiting for a poker job at the FQ's. Took a slot job at Binions while waiting.

Help light came on and I responded to a $1 machine.
Guy had 6 or 7 racks on tokens he had won.
Complained he had a Cherry for $2 payout and the machine did not pay.
I called the tech. Turned out the guy had been free pulling the machine for some time.
He had his whole win confiscated over not getting a $2 payout.
People are really stupid!!!!