How a carbon copy of bitcoin could solve anything?

You still need to store all transaction of all random guys. Now those transactions are split into two separate blockchains, but they occupy the same space on your HDD (in fact even little more).

And yes, there can be at most one winner. That means, it is possible, that there will be no winner at all. I.e. all free decentralised cryptocurrencies dieout. And to be honest, greed drives us now to that worst, no winner, direction.