为什么来自VSTS nuget feed的nuget想要多次安装相同的包并抛出错误？

Question

我在Azure中使用Durable Function App实现了REST Api，它使用了netstandard2.0，我在此解决方案中也使用了netstandard2.0。其中之一是合同项目。

还有另一种解决方案，UAT测试为此解决方案。原因是，Specflow仍然不适用于.Net Core，它仅适用于.Net Framework。能够测试Api我需要Api的合同。这就是我需要包含REST Api解决方案合同项目（这个是netstandard2.0）的原因。这种依赖关系由nuget管理。

当我想在Specflow项目（使用netstandard2.0）中安装Contracts包（使用.Net Framework 4.7.1）时，我得到以下错误。

我尝试了什么：

我重新启动Visual Studio几次，因为我经历过，当.Net Core或.Net Standard项目正在使用时，它有时会变得疯狂。重启没有帮助。
我从JetBrains Rider打开了这个项目，但它没有在存储库中看到netstandard2.0 nuget包。我认为这是因为该项目使用.Net Framework 4.7.1而不是Net Standard 2.0
我看到了错误Cannot create "C:...REST.Api.dll" because a file or directory with the same name already exists.。所以，我删除了解决方案包目录下的所有包。我还在Visual Studio中删除了缓存。但是，下次我启动Visual Studio并尝试安装包时，再次出现相同的错误。
我还尝试在我的机器上使用控制台安装软件包（nuget.exe install ...）。错误是一样的。

如何解决这个问题？我从.Net Framework 4.6及以上读过，.Net Core可以参考.Net Standard库。

Attempting to gather dependency information for package 'REST.Api.1.0.0-20180305-154726' with respect to project 'MasterData.Features.HttpClient', targeting '.NETFramework,Version=v4.7.1'

Gathering dependency information took 861.8 ms

Attempting to resolve dependencies for package 'REST.Api.1.0.0-20180305-154726' with DependencyBehavior 'Lowest'

Resolving dependency information took 0 ms

Resolving actions to install package 'REST.Api.1.0.0-20180305-154726'

Resolved actions to install package 'REST.Api.1.0.0-20180305-154726'
  GET https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg

Retrieving package 'REST.Api 1.0.0-20180305-154726' from 'Sayusi Ando's Digital Library Packages'.
  OK https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg 2343ms

Installing REST.Api 1.0.0-20180305-154726.

Error downloading 'REST.Api.1.0.0-20180305-154726' from 'https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg'.

Cannot create "C:Usersusername.nugetpackagesREST.api1.0.0-20180305-154726lib
etstandard2.0REST.Api.dll" because a file or directory with the same name already exists.
  GET https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg
  OK https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg 462ms

Installing REST.Api 1.0.0-20180305-154726.

Error downloading 'REST.Api.1.0.0-20180305-154726' from 'https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg'.

Cannot create "C:Usersusername.nugetpackagesREST.api1.0.0-20180305-154726lib
etstandard2.0REST.Api.dll" because a file or directory with the same name already exists.
  GET https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg
  OK https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg 464ms

Installing REST.Api 1.0.0-20180305-154726.

Install failed. Rolling back...

Package 'REST.Api.1.0.0-20180305-154726' does not exist in project 'MasterData.Features.HttpClient'

Package 'REST.Api.1.0.0-20180305-154726' does not exist in folder 'C:VSTSREST.QA.Featuressrcpackages'

Executing nuget actions took 3.51 sec

Error downloading 'REST.Api.1.0.0-20180305-154726' from 'https://xyzrepository.visualstudio.com/_packaging/689a2aa0-1e6a-4f39-8389-250b4ad44db8/nuget/v3/flat2/REST.api/1.0.0-20180305-154726/REST.api.1.0.0-20180305-154726.nupkg'.
  Cannot create "C:Usersusername.nugetpackagesREST.api1.0.0-20180305-154726lib
etstandard2.0REST.Api.dll" because a file or directory with the same name already exists.

Time Elapsed: 00:00:05.5462783