The lottery has been rooted in Thai culture for the longest time.
They are very superstitious about the way they come up with the number

People do all kind of things just for the hint, like worship old trees,
calculate from dream or important events,
the most popular one is to worship supernatural stuff
 

The mutated animal is one of the top hit.
But how come this eight-legged frog or two-headed cow keep popping up so much Is it just another coincident?
Or it could be some cooperate behind this.