Why should Uber be valued higher than Lyft?
That's a pretty crude comparison, but I'm just pointing out that just cause someone comes along and makes a clone of something doesn't mean it will be worth more than the original even if it is technologically superior.
It's true that forking a cryptocurrency required much less work than starting a company, but I don't think that the value comparison is that different.
If people believe Bitcoin should be valued higher than a clone of Bitcoin even if the clone is better, Bitcoin will be valued higher.