MAVLINK message requests

If there are multiple devices requesting message rates over MAVLINK, does Ardupilot send those messages at the specified rate to all components in the MAVLINK system? (i.e. companion computer and ground control) I have a companion computer (SAMD21 microprocessor) requesting attitude at a different rate than Mission Planner, but I am getting Raw IMU messages on the companion computer. Is this something I should expect?

When I connect my CC to TELEM2, I get the messages at default rate, I guess, without requesting them.
I tried sending MAV_CMD_SET_MESSAGE_INTERVAL msg id set to 33 (GLOBAL POSITION INT) and interval set to 100000(10Hz) but nothing changed at measured rates for that message. But when I send REQUEST_DATA_STREAM with MAV_DATA_STREAM_ALL and rate set to 10. I observe 5+ rates for messages that I interest not only POSITION.
Do anybody know the proper way of requesting messages along with the GCS?

P.S I read the documentation.

What version of the code are you running?

I reverted to ArduPlane 3.9.11 since telem 1 and 2 ports does not work well when used at the same time.