How do I run 2 Android phones on a PC simultaneously So that DroidCam for number 1 & TC games screen mirror for number 2? I have 2 android phones and i want to connect both of them to my PC via USB cables like this: 1- Motorola Moto G3 5.1.1 (Lollipop) goes to DroidCam app for using as a webcam. 2- Samsung S4 zoom (KitKat) goes to mirror screen android to PC app called &quot;Tc games&quot; for screen share and control my phone from my PC. Right now i have Universal Adb Driver installed on PC and i can't run both programs at the same time. this message pops up when i use DroidCam at the same time with Tc games (adb server is out of date. Killing...). How can i connect Motorola always to DroidCam as a default, and Tc games to Samsung and run both of them at the same time without any problem ?
Applications like DroidCam or Scrcpy that require adb to work often include an own version of adb. For DroidCam you can see it in the sub-directory adb the three files that belong to adb:

adb.exe
AdbWinApi.dll
AdbWinUsbApi.dll

However adb is designed to be present one time on a system because when it starts it remains loaded invisible in the background.
Now if a program has it's own adb version it prefers this versions and therefore when it starts it's own adb version the previous adb daemon running background is killed and replaced with the different adb version.
In your case the message adb server is out of date. additionally indicates that you have two different versions of adb installed and the newer version kills the older version that was already running (old version = out of date version).
Some programs like Scrcpy allow to specify via environment variable where adb.exe is located so that you can redirect it to one adb versions that is available on your system.
I am not sure if DroidCam also supports such an environment variable.
But in any way you should &quot;equalize&quot; all adb versions you have installed:

Search your system where it has adb.exe installed
On each found adb.exe execute adb.exe --version and identify the newest version (the version installed with Android Studio shows at the moment Android Debug Bridge version 1.0.41 - Version 30.0.2-6538114
From the newest adb version copy the three files adb.exe, AdbWinApi.dll and AdbWinUsbApi.dll to the other locations adb.exe was found overwriting the existing files.

This should at least solve your problem that the adb versions installed have a different version.