Same namespace but different dll version/code

Reference 2 dll. both library have a 'System.Threading' namespace but in different version. Unity showing :> error CS0433: The type 'TaskScheduler' exists in both 'System.Threading, Version=1.0.2856.102, Culture=neutral, PublicKeyToken=31bf3856ad335e22' and 'Unity.Tasks, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' In Visual Studio we can set the dll alias name to different the library. But Unity is not supported 'extern alias' -> [reference][1] How can I solve it? Thanks in advance. [1]: https://feedback.unity3d.com/suggestions/add-support-for-reference-aliases-slash-extern-alias