Twinsets - same model regulator or not?

[Rick Murchison]

FWIW, the origin of the question was in regards to concerns of model wide failures re: computers. Someone suggested that they chose different redundant computers in case an inherant model/algorhythm prone failure knocked both computers out at the same time. I then asked if those same people chose different first stages on their doubles in case a model specific failure knocked both out at once too.
I was wondering if the same risk analysis carried throughout the full range of their gear selection.

Apples & oranges... electronics can easily succumb to the same bug in the program at precisely the same time, while good old purely mechanical devices like regulators just don't do that, as parts are never truly identical and therefore just don't fail at the same time.
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As for the "different regs" question, some folks like to have the same regs (like me) and others like to comply with GI3's original DIR paper and use something "non air balanced, low performance."
The other reason to use two different regs is because you want to upgrade from your original reg but can't afford (or just don't want) to buy two yet. That's a perfectly legitimate reason to use two different regs so long as you don't exceed the safe operating envelope of the lower performance reg.

Rick