Ollie ~ I couldn't get this to work in the order you entered however I still got a decent deal. By using TUI20 first on the $36.00 TUI duo the total is automatically adjusted to $20.00 which removes the free shipping. You can still use the CDPR20 on top of that for an additional 20% off though.
What I did: I added the $36.00 TUI smoothie duo to the cart first, followed by the CDPR20 for 20% off and then used TUI20 (2 for 1 deal) which brought the total down to $16.00. With tax, my order was $21.36 for the two which is like getting 2 for the price of 1 + free shipping for (overpriced) $20.00 conditioners.
Thanks for sharing.