Since MultiMedia has (marginal) wasapi support (5.9/5.10?) the audio devices are listed double for both input and output devices. The difference of the double entries can only be noticed by retrieving the supportedChannelCounts() method. The 1e device entry gives a supportedChannelCounts list of 1 - 18 channel ( probably the winMM ) , the 2e entry of the same device has only 1 or 2 supportedChannel list entries ( probably the wasapi shared device ).

Removing the "qtaudio_wasapi.dll" plugin from the deployed "audio" directory will only list the winMM ( 1-18ch devices ) so it's wasapi related

I would suggest one of the following:

• a filter for only getting only winMM or Wasapi devices
• a different device name ( added wasapi to it )
• or a QAudioDeviceInfo::isWasapi() methode

Steps to produce: Compile and run Qt 5.12.3 MSCV2017 64bit4 example project "Audio Devices Example"