It would be worth the same at the height of the fork. Critical error going unnoticed would be highly unlikely with something open source.
Discussion
It wouldn't be worth the same because someone would have to be stupid enough to actually buy it. Bcash was worth about .2 btc at the time of the fork.
You right, you right... I was thinking about the fact that they would have the same amount. They may be worth a fraction but the real price would be artificially lower too. Food for thought.