Wow, scary for sure. I am glad you got home in time to save them.
My single experience with cat break away collars is that they do not always break when necessary. The neighbor's cat, wearing a break away, got itself inside their box spring mattress and the collar got twisted on a loose wire. We had to slash apart the mattress to get the cat loose. Happy ending, but way scary for the cat and us. I still have scars from the claws.
We do not put collars of any type on unattended animals. Sparky is in a harness 24/7, and constantly attended, but that is just until he learns that trying to jump when being carried is a bad idea for a Chihuahua. The harness makes a great handle.
Figuring risk is a tuff one. My opinion is that if your dogs have never escaped, and you know that one has the habit of chewing the collar on the other dog, keeping the collars on is a greater risk than having them off.
Side note on risk and collar types...Haltis and other head harness are more likely to cause spinal injuries than neck collars. My Vet. and all the trainers I know recommend not using them due to the risk.
I use a dual system: the dog has a harness and a collar linked with a splitter so that the first leash correction is felt on the neck, but if they continue to pull, the force gets transferred to the harness saving their necks. With big stubborn dogs like my Zita, they get the collar with the plastic-tipped prongs for lesson 1.