The other thing which makes me suspicious (although I'm not accusing the OP obviously) - is that in Box 1, the pen underneath seems to be different from the pen being used with the alteration/overwriting.
Is the OP claiming that the conductor on the train first entered the date in the wrong place with one pen, and then corrected it using a totally different pen, whilst making it look fraudulent, only for on the second day, by sheer bad luck, a 30 happened to have ended up looking like a 31?
Is it theoretically possible that a fraud COULD be committed by dating Box 2 with the 30th, and travelling on the 30th, and then the OP adjusts this himself to the 31st, tries to travel on the 31st and offers an excuse of it being a "mistake", only for a conductor to not accept that, and insist that he dates another box, correctly?
Not saying that is what happened, but the entire thing seems odd.