I have no idea what the reasoning behind it was then, but it was a standard carried over from yugoslav times (usually 3 gas + 1 electric or 2+2) :) So yeah, could be redundancy...
I remember only one gas outage (some repair work done somewhere and they closed the valves) but there were quite a few power outages, where you had to use a lighter.
https://i.imgur.com/rHDaZxm.png <- something like this was standard, also back in the time the colors were browner ( eg. https://i.imgur.com/RJkq5GK.png ) :)
The modern variants look more like this: https://i.imgur.com/iJvKQjy.png or with inductive heat instead of resistive: https://i.imgur.com/BOetXJz.png
I remember only one gas outage (some repair work done somewhere and they closed the valves) but there were quite a few power outages, where you had to use a lighter.