Here is what I've done. I've taken the Std vol + and added 20 additional copies of the last 4 words (21 copies of the word total).

The 1st way means red becomes 004A and blue stays 0002.
The 2nd way means red stays 0022 and blue becomes 002A.

Both of these codes still only change the volume up by 1 db.

I used the original Ext Vol + hex as a learned key and it behaved like the original Std Vol + as a learned key. A quick press was 0.5 db and press and hold advanced the volume.
I don't know if it is worth a try to use the Ext Vol + and create the same experiment but that'll have to wait until later.