Am I missing something? (white balance)

Still learning DR but I found something that doesn't make sense to me, but maybe I'm missing something..

Try this ( irl or just in your head):

Pick a snowy shot, in one node you set the white balance with the white balance picker. The result gives you back temp: -900 and Tint: 24

In the next/other node (serial/parallel) you kind of undo that by setting the temp to +900 and the Tint to -24.

For me it makes sense that when I disable them both there shouldn't be any difference.. But there is a very noticeable difference. What am I missing?

Is it similar to the percentage problem.
If you take 100 subtract 20% you get 80 then add 20% you get 96.

Pick a snowy shot, in one node you set the white balance with the white balance picker. The result gives you back temp: -900 and Tint: 24 In the next/other node (serial/parallel) you kind of undo that by setting the temp to +900 and the Tint to -24.

Ignore the numbers. Look at the results on a calibrated monitor and on a Vectorscope & Parade Waveform Monitor.

If you want accurate Color Temperature adjustment, use the OFX Chromatic Adaptation plug-in and switch it to Color Temperature mode, then use the slider to get a reasonable overall balance. This will work, at least in cases where you don't have access to the Raw controls. In extreme situations (like very warm/yellow 3200° material shot with the camera stuck in 6500°), you might have to add a couple curve nodes to pull some yellow and/or balance the picture with Primaries. Temp & Tint alone are not enough.