"mscorlib,Version = 4.0.0.0"和"mscorlib,Version = 2.0.5.0"之间存在冲突

Question

在玩ASP.Net Core时,我尝试引入自己的自定义代码库并获取以下消息:

无法解决"mscorlib,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089"和"mscorlib,Version = 2.0.5.0,Culture = neutral,PublicKeyToken = 7cec85d7bea7798e,Retargetable = Yes"之间的冲突.任意选择"mscorlib,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089".

无法解决"System,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089"和"System,Version = 2.0.5.0,Culture = neutral,PublicKeyToken = 7cec85d7bea7798e,Retargetable = Yes"之间的冲突.任意选择"System,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089".

问:是否有可能使两个版本"一起玩得很好"？
问:即使尝试也是个好主意吗？

注意:
运行update-package -reinstall卸载所有对Entity Framework,Unity等的引用......所以这不是"修复".