What might cause a device to show up twice on a Mac?

[xobs]

I have a small script to list devices. This can be useful to get an idea of the bus topology.

I had a mac user with something very, very strange:

2e8a:000c:E6616408431E722B @ 00/1/1/2 Raspberry Pi - Debugprobe on Pico (CMSIS-DAP)
2e8a:000c:E6616408431E722B @ 00/1/1/3 Raspberry Pi - Debugprobe on Pico (CMSIS-DAP)

That is, one device started showing up on two ports. While there was something plugged into 0/1/1/3, it was a different device. This persisted across multiple runs of the script, and with different programs that use nusb. After unplugging things and plugging them in again, port 0/1/1/3 started showing up as the correct device rather than a duplicate of the debugprobe.

Can you think of anything that could cause this? Or what I should look for next time?

[kevinmehall]

Weird. First thing to check if it reoccurs would be whether it shows like that in ioreg -p IOUSB -l to see if IOKit sees it like that.

It would also be useful to see the nusb debug log, e.g. set RUST_LOG=nusb=debug with the env_logger crate.