How does DllImport identify the newest .dll-Version?

I have a winforms application and can call an external method located in a third-party-dll successfully. This dll-file is located anywhere on my machine.

[DllImport("ext.dll")]
public static extern int Print(string cmd);

Yesterday i get a batch from the company developing that ext.dll because of an internal bug located in the Print-Method. The batch contains a bug-free version of ext.dll.

Now my question is: How does DllImport find this new bug-free version located anywhere on my machine and use it instead of the old one? Additional Information: I use DllImport because i can not add the dll-file via "Add Reference" in VS.

Thanks in advance! Regards Walter