Looking at the felix.se and felix.at websites, it seems that probably Felix Austria was created in 1958 to serve the Austrian market. The Swedish website says Herbert Felix (a Czech immigrant to Sweden) started making pickles in Sweden in 1939. They use basically the same logo, and they are both owned by Orkla, so I suspect that Felix AT was a spin-off at some point to serve the Austrian market specifically.
Nope, apparently it's the same Czech/Austrian Herbert Felix who founded the brand in Sweden then brought it to Austria[1].
Now I'm itching to try the Swedish Felix and see how it compares to the Austrian one.
Also TIL that: "Sweden has the world's highest consumption of tomato ketchup, and Felix is by far the biggest brand, almost twice as big as its nearest competitor."
edit: Felix Austria is a daughter company of Felix Sweden, founded by the same Mr Felix a couple of decades later.