The 2 sided sprite creates a physically 2 sided sprite, with a front and back face. Both display the same sprite - it is so both sides light correctly, not for the use case you're describing. Set it in the sprite collection editor - render mesh -> Double Sided.
What you're requesting is a real double sided sprite - as in 2 sprites back to back. Its easily doable - you just need to change the shader as I described in the previous post. Normally sprites are visible from both sides, but you want to make them single sided, so you can place 2 sprites back to back.