Library Manager tries to install a library already there

I got a project using a library “esp32modbusRTU”. I looked for it in the platformio Library Manager, found and installed it. In the platformio.ini I added the library to the lib_deps section:

platform = espressif32
board = az-delivery-devkit-v4
framework = arduino
lib_deps =
  Adafruit GFX Library@1.7.5
  Adafruit SSD1306
board_build.partitions = default.csv

When building the project, I always am getting these lines:

Looking for esp32modbusRTU library in registry
LibraryManager: Installing id=5876
esp32ModbusRTU @ 0.0.2 is already installed

Why does this happen and how can I prevent it?

So you installed it in the global library storage by clicking on the Install button in the GUI?


Then this is correct since it’s already in your C:\Users\<user>\.platformio\lib\esp32ModbusRTU folder. For users which do not have this library globally installed it will download it into the local lib/ folder of the project.

Well, yes, it is in both locations. But why? I did not manually install it. The same applies to all the other libs in the lib_deps section, but without that message in the build log. Again: why?