Your experience makes no sense to me.
The laws of physics say that extreme cold should DECREASE the pressure exerted by the butane, not increase it. If you had been in the Mojave desert in extremely HIGH temperature, I would expect the possibility of increased pressure induced leakage, not in extreme cold.
This sounds like a "Challenger O-ring" type seal failure QA problem.
Were both lighters the same brand?? El cheapo checkout line type, or good quality??
Any other FR hunters or outdoor types have a similar issue with butane lighters??
They were different types of lighters. I was a past aerospace fuel systems designer including an “x-files” fuel system. You would think I might know a few things about seals, lol. I would say seal or o-ring failure, probably from a combination of low temperature and poor chemical resistance to Butane. I seriously doubt most lighters have improved much from the mid 80’s. It still would be interesting to look at some of the operating temperature engineering specs for individual lighters. Example: 5 out of 13 rubbers are unacceptable for butane use, including the very best for temperature gradients. https://mykin.com/rubber-chemical-resistance-chart
“The laws of physics say that extreme cold should DECREASE the pressure exerted by the butane, not increase it.”
It is possible that the lighters contents were released due to the contents suffering negative pressure (vacuum) because of the cold.