If an AI failure gets you into the life threatening situation, something is wrong with your dive plan to begin with.
Why would you need two transmitters?
One for the back gas and one for the stage. ;-)
Why would you need two transmitters?
... or for a buddy, or even several transmitters for all the group if you are a dive master.
... or for multi gas dives
Why would you need two transmitters?
I have three PPS transmitters!
One for my main regs, one for my pony regs (for when I dive with a pony or my doubles) and one on my backup regs (the regs I use when my main regs are in for service).