I've been questioning this idea myself. The outcome i came for is that your calculations are wrong.
Try to see 700000/2 in 3 lifetimes. this way the 500000/0 is 500k per lifetime, and 700000/1 is in 2 lifetimes, rego 350k per lifetime. I know it sucks for those that did 600k/100k in those lifetimes since they have no proof.
Any closer to the correct amount is... well quite impossible to prove...
Ahh I see what you mean. Thanks for clearing that up.