Double sided shader

[aorikasa]

This is related to my "Lat-long render export" (https://planetside.co.uk/forums/index.php/topic,29772.0.html) question but I wanted to make this as a separate topic.
The only way I know to render out a lat-long image of planet from spherical camera is inverting the planet's radius by putting negative number.
But I'm wondering if there is a way to set the shader to be double sided so textures can be seen even though normals are facing away from camera.
If there are tricks or workarounds, please let me know. Thank you in advance!

[Dune]

If it's just to check things out and see something in the preview, I think a second planet/sphere (+radius) will work. Turn it off when rendering, if that's even needed.

[aorikasa]

Thanks Dune. I guess there is no good way to make the shader double sided. Thanks!