Yes, you are right. For the plugin, the Octane lights are like any other object, so this feature is also overriding the light materials.
I'll try to find a solution for this problem in the next build, but the workaround is easy: you only need to add the light objects to the override "Exclude Objects" list.
Thanks for reporting this issue,
Computer Graphics Software Developer
Octane plugin development and support: LightWave and Houdini