Need a way to reference 2 different versions of the same 3rd party DLL
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I have a solution with 2 projects: Proj1 and Proj2, where Proj1 is the startup project.

Proj1 references Proj2 (in order to call Proj2's class) and it has existing code that also references a 3rd party DLL called A, versioned at 1.0.0.0. 

Proj2 references the same 3rd party DLL A, but it references it at version 2.0.0.0, since the class in this project needs newer implemenation that was not available in 1.0.0.0.

So far I've tried the following:
1. Switched "Specific Version" to true when referencing A
2. Added a folder called "v2Folder" in Proj2 and added A v2.0.0.0 to it, set its "Copy to Output Directory" to Copy Always
3. Added "probing path" to app.config to point to the sub-folder with the v2.0.0.0 DLL

What I want is to see A v1.0.0.0 in the normal \bin\ folder, and A v2.0.0.0 in \bin\v2Folder, and I expect that when I run my Proj1.exe, Proj1's old code will still call A v1.0.0.0's methods, and only call A v2.0.0.0's methods when calling what is implemented by Proj2.

The problem is, when I build my solution, v1.0.0.0 got replaced by v2.0.0.0, the build log has something like "No way to resolve conflict between "A, Version=2.0.0.0, Culture=neutral, PublicKeyToken=blah" and "A, Version=1.0.0.0, Culture=neutral, PublicKeyToken=blah". Choosing "A, Version=2.0.0.0, Culture=neutral, PublicKeyToken=blah" arbitrarily.".

Can someone help?