I'm on ubuntu 17 and i just added a few vpn options. I noticed you can turn all of them on, but which one takes precedent? If all of them are on, do they just fall back on the other if one of them fails?
That highly depends on how they are configured. Some tunnels are configured to route only traffic that is destined for the other end of the tunnel, while others are configured to route all traffic. Which one takes precedent (where your traffic goes) is highly dependent on any routes they might setup and the order in which you enable them. If you'd like an answer specific to your configuration, you'll need to provide those configurations and your routing table (both while they're connected and disconnected).
Guessing from the names I'm going to assume both of those tunnels are configured to pass all traffic. If that's the case, it's likely that the second tunnel you enabled established it's tunnel through the first tunnel you enabled. This probably doesn't make you any more secure and will likely slow down your connection.