Doubtful. That'd require a custom bill mechanism, and Kraken noted that they're using a standard, off-the-shelf bill acceptor -- the same type you'd find in a vending machine.

That doesn't help too much does it? Since you aren't permanently losing the money using a few 10s of thousands in cash isn't such a big deal.

True, but at least you would need unique bills to run through, and law enforcement can then track those bills.

So you basically need access to a cash business for a supply of fresh bills. Also for how long do they keep the serial numbers? After a certain amount of time it is possible for the same bill to enter the machine legitimately.

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Law enforcement can laugh at you when asked to track those bills...