Systemview microlib microVision

I am trying to instrument a program where we use RTX kernel and microlib on uVision.
I understand that there are no porting or official support for RTX, that's ok. I am starting from scratch from SEGGER_SYSVIEW_Config_NoOS example and then I'l instrument events or tasks.
My problem is that using microlib I get following errors, even when following instructions from https://wiki.segger.com/Keil_MDK-ARM#RTT_in_uVision

Error: L6200E: Symbol _sys_open multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).


Error: L6200E: Symbol _sys_close multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).


Error: L6200E: Symbol _sys_write multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).


Error: L6200E: Symbol _sys_istty multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).


Error: L6200E: Symbol _sys_seek multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).


Error: L6200E: Symbol _sys_flen multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).


Error: L6200E: Symbol _sys_read multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).


Error: L6200E: Symbol _sys_ensure multiply defined (by sys_io.o and segger_rtt_syscalls_keil.o).

I am using toolchain version 5.39.2.2 with c compiler armcc v.506 update 7 (it's some legacy project that I'd like to profile, hence the old version of ide and compiler)

I can comment out the _sys* functions that lead to errors, but then of course sysview does not provide any output.

Any hint?
Also a "you can't do it" would be fine, then I will switch to different approaches and evaluate systemview on new projects.

K.R.

Luca.