Yep, the orange channel on a 3channel Recto is more like the red on a 2channel, the red channel on the 3chan is a unique channel.
The 3channel Recto does have one channel more than the 2chan, so one of them must be different, right?
This is what the Recto manual has to say:
CHANNEL 3 is optimized for the legendary MODERN mode with a range of PRESENCE far exceeding that of CHANNEL 2. This channels’ PRESENCE picks up where CHANNEL 2 leaves off and allows top end harmonics that are downright dangerous. The trade off here is that for VINTAGE and RAW the PRESENCE is hyperactive and must be dialed with care to achieve the more warm and round sounds. You can think of it like this...a Presence setting equivalent to CHANNEL 2’s PRESENCE Control set to 5:30 (maximum), is found in CHANNEL 3 at approximately 10:00 on CHANNEL 3’s PRESENCE Control. This means that the whole range is compressed for these more vocal sounds and the resolution for brighter sounds is expanded.
That gives a bit of an explanation for the red/vintage as well.
Hope this helps!