Hi Serge,
I have a Pi 3 with two USB sound card interfaces. I see this behavior regularly. The numbering of the interface depends on the ordering of device discovery during boot. Fortunately, there is a way to specify devices based on name, which may help you. Here are the devices I have on my pi.
**** List of CAPTURE Hardware Devices ****
card 0: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
? Subdevices: 0/1
? Subdevice #0: subdevice #0
card 1: Device [C-Media USB Audio Device], device 0: USB Audio [USB Audio]
? Subdevices: 0/1
? Subdevice #0: subdevice #0
The "USB Audio CODEC" interface is my HF rig and the "C-Media USB Audio Device" is my VHF rig.
In my direwolf config files I have the following entry for my HF rig.
ADEVICE? plughw:CODEC,0
and for my VHF rig I have the following.
ADEVICE? plughw:Device,0
But this syntax matches on part of the device name, rather than the number. So you'll get the right device regardless of what order the sound cards are discovered.
Hope that helps,
-Brent
Brent WG0A