Is it normal to see two varnishd processes?
Yes, it's normal. One handles normal connections, the other handles the admin.
You can check which is which by using netstat:
# netstat -ntlp | grep varnish
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 8935/varnishd
tcp 0 0 127.0.0.1:6082 0.0.0.0:* LISTEN 8934/varnishd
As you can see one binds to the admin port (6082) on the loopback interface, while the other binds to the main port (80 in my case and in most).