Why can't I set two vhost in my apache?
The problem isn't with Apache, it's with your /etc/hosts file.
You can only have one line in the hosts file per IP address. So your hosts file should look like this:
127.0.0.1 hwy.local www.hwy.local test.app www.test.app
with all the entries for 127.0.0.1 on one and the same line.