There isn't any "Area lights" in Octane, they get converted to meshes (planes).
And that's why they have shadows.
But that might be one for the "wish list"/feature requests that:
- Area lights by default don't have "Shadow visibility" set to false (just as "Camera visibility" is set to false by default)
- There's an "Shadow visibility" option for area lights (this exists for meshes in the Blender UI, would be nice to have it for area lights as well).
Personally I tend to just stick with planes/mesh lights, but area lights can be handy and in some ways "easier" to work with..
Windows 10 Pro - AMD Ryzen 7 2100X 8 core 3.70GHz - 32GB RAM - GeForce GTX 1080 8GB
Octane Prime - Blender Plugin user