I was also getting the same error. But now it is working for me. First you install I2S microphone as shown here: https://learn.adafruit.com/adafruit-i2s-mems-microphone-breakout/raspberry-pi-wiring-and-test
After that while you are installing I2S amplifier go to the detailed installation section and skip the first 2 steps and start from "Create asound.conf file" and at last reboot your pi.
Update: Please note that using the aplay.service which constantly sends audio to the audio output will break the microphone.
