It could be the train is taking off and flying into the sky...
Seriously, it is shocking quality control. It is still for sale at the RM and so they should be able to send you a proper replacement. Otherwise, I would ask for a refund and buy something else.
I have taken a look at mine I have one with an 8 over an 8 there appear on mine to be two types of 8 used a small 8 and the much fatter 8 so I am guessing the one was overpunched on the the other. I only have a population of 10 and tend to look for "errors" so not a scientific collection. Lots of 5 over 3's and 5 over 3 and 2 and one with a 1 over a 1 . Not sure if that helps but all these tiny things make a coin have extra personality
Yes, very sad, and of course it took dear Kenny Everett too.
I had a 38 year old studio engineer in the workshop this week who had never heard of Kenny Everett.....how quickly people are forgotten.