What s happen here?

You got a Polyploidy scientific term for plants with extra-developed areas; elephantiasis, in other words, for the plant world. In the case of cannabis, the plants are overall much bigger than their regular counterparts of the same strain. That said, this is not a trait that can be passed to other plants, nor does it seem to survive genetic crossings with other strains. There is anecdotal evidence that this mutation can lead to wildly big yields and high potency, as there is double the amount of genes compared to a normal plant. However, this does not appear to be scientifically verified. If it happens to one of your plants, though, let it grow and see what happens!