SW4STM32 and SW4Linux fully supports the STM32MP1 asymmetric multicore Cortex/A7+M4 MPUs

   With System Workbench for Linux, Embedded Linux on the STM32MP1 family of MPUs from ST was never as simple to build and maintain, even for newcomers in the Linux world.
And, if you install System Workbench for Linux in System Workbench for STM32 you can seamlessly develop and debug asymmetric applications running partly on Linux, partly on the Cortex-M4.
You can get more information from the ac6-tools website and download two short videos (registration required) highlighting:

System Workbench for STM32

Simultaneous debugging of multiple targets

they are likley issue and limitation on the various s/w (openocd, stlink driver etc ...) when you have mtulipe instance of the same usb -device . certainly they operate on the first device they found and we have no way to change that at the moment like givin the serial number that would ne a nice feature.

Regarding debug wihtout flashing that is like “debug attach to a running target/process”,
but i think that type of debugging is not suported at the moment by the plugins,

how you can do that take an ac6 debug configruation, duplicate it , rename to smthg like “xx no load”
go in the debug configuration startup pane , uncheck the “laod image”. voila..

Of oourse if you use that config and the loaded binary doesn’t match .elf image nothing gonna match (not even initial break at main)