I have heard of this happening before in American pressing plants that created punk and indie records in the late 80's and early 90's. Often reported as accidents, they were in fact anything but. Bands later admitted this.
Some pressings that were colour vinyl were different colours because of lack of materials and different shades were printed over the scale of the batch. Also sometimes another press would happen because they ran out of materials and then 're-appear' at a later date.
There is presumably an uber collector that will find value in this mispresses but personally I wouldn't want it. Personally, I would sell it, donate a % to charity and by the proper one.
Lets face it, the world of collecting seeks a good mystery and thats why these accidents happen.