I think I would have to leave everything split equally because my will is more than just a financial sum, it's a sort of gesture as well, I would love my children equally (don't actually have any) so I'd want to treat them equally.
FWIW, this situation has actually happened in my family, though with a twist.
I am one of three siblings. As children, we were all given some premium bonds as a gift. During childhood, I won a significantly big prize on my premium bonds - lucky me! But my parents took control and decided, to "make things fair", that my winnings would be split equally between the three of us. I wasn't really old enough to argue a case against this.
Some years later we are all in our early 20s, my brother won a similarly significant prize on the lottery, and treated us to a meal out but kept the bulk of it and bought a house.
I should live and let live/let it go/etc, but it's actually really affected my relationship with my family, because he was able to live his entire adult life very comfortably, whereas I lived in poverty and only managed to buy my first home in my 40s. I'm still resentful of the decision my parents made too.
That said, I'd still expect my parents' will to be split equally.