it's an Aqualung of some sort, looks like a calypso.
Octopus hose shot out of the first stage. One of two things. Crimp failed, or the first stage hose threads failed. Crimp failing is not uncommon, threads failing is something I've never heard of.
Crimp failure could likely have been caused by abuse of the octopus if it got caught on something and they pulled on the crimp fitting. This is a very common issue with the "golden triangle" regulator system where the octopus is often seen dangling behind the diver waiting to get caught on something
Brand/model of the regulator is 99.999% chance irrelevant as I would bet quite a bit that the crimp is what failed not the first stage. Owning your own reg wouldn't prevent