Reproduction steps:
1. Open the attached user's project "UnityAndroidMicrophone.zip"
2. Build for Android
3. In the app right side press the square icon for Debug Console
4. Press the "List" button to list all recording devices
5. Press "Start-1" to start recording with 1 Microphone device
6. Repeat step 4

Expected result: only one "Microphone.IsRecording True" is returned
Actual result: all recording devices return "Microphone.IsRecording True"

Reproduces on: 2019.4.11f1, 2020.1.6f1, 2020.2.0b4
Could not test on 2018.4 due to only one microphone being listed when checking the microphone list

Reproducible with these devices:
N/A, Samsung Galaxy S9 (SM-G960F), Android 8.0.0, CPU: Exynos 9 Series 9810, GPU: Mali-G72
VLNQA00316, Samsung Galaxy Note10 (SM-N970F), Android 9, CPU: Exynos 9 Series 9825, GPU: Mali-G76

Could not test on these devices due to not showing any Microphone devices in the Debug window:
N/A, Lge LG V50 ThinQ (LM-V500N), Android 10, CPU: Snapdragon 855 SM8150, GPU: Adreno (TM) 640

Could not test on these devices due to an error parsing the package when trying to install the APK:
VLNQA00024, Xiaomi Mi 5 (MI 5), Android 7.0, CPU: Snapdragon 820 MSM8996, GPU: Adreno (TM) 530

Notes:
-Tested on Mono and IL2CPP