如何抑制Tasks.Task不同的PublicKeyToken错误

I noticed I get one line of code underlined. If I understand correctly, the error means that I have two different versions of some library in my solution. However the error doesn't stop the solution from compiling and everything works like it's supposed to work. What is the reason of Visual Studio underlining this line of code? How can I stop this from happening? Where to look for some incoherence?I noticed I get one line of code underlined. If