Error: An item with the same key has already been added

I am not sure if it's a paket bug but as it have something with the restore target and dependency management I am posting it here for now.

I have a project with this structure:

Fulma.fsproj:

• Is a netstandard2.0 fsproj
• TargetFramework: netstandard1.6

Fulma.Extensions.fsproj:

• Is a netstandard2.0 fsproj
• TargetFramework: netstandard1.6
• It include a reference over Fulma via paket.references

Docs.fsproj:

• Is a netstandard2.0 fsproj

• TargetFramework: netstandard2.0

• Include references on the twos others project via ProjectReference attributes

  <ItemGroup>
     <ProjectReference Include="../src/Fulma/Fulma.fsproj" />
     <ProjectReference Include="../src/Fulma.Extensions/Fulma.Extensions.fsproj" />
   </ItemGroup>
  

When running dotnet restore on Docs.fsproj I got this error:

docs feature/conversion *$ = $ dotnet restore
  Paket version 5.92.0-beta003
   - C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\docs\obj\docs.fsproj.netstandard2.0.paket.resolved created
   - C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\docs\obj\docs.fsproj.paket.clitools created
   - C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\docs\obj\docs.fsproj.paket.props created
   - C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\src\Fulma\obj\Fulma.fsproj.netstandard1.6.paket.resolved created
   - C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\src\Fulma.Extensions\obj\Fulma.Extensions.fsproj.netstandard1.6.paket.resolved created
  Performance:
   - Disk IO: 56 milliseconds
   - Runtime: 2 seconds
  Restoring packages for C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\src\Fulma\Fulma.fsproj...
  Restoring packages for C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\docs\docs.fsproj...
  Restoring packages for C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\docs\docs.fsproj...
  Restoring packages for C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\src\Fulma.Extensions\Fulma.Extensions.fsproj...
C:\Program Files\dotnet\sdk\2.0.0\NuGet.targets(102,5): error : An item with the same key has already been added. Key: (Fulma, 0.2.0-beta-002) [C:\Users\mange\Workspace\Github\MangelMaxime\Fable.Elmish.Bulma\docs\docs.fsproj]

I tested it with this version of paket:

• 5.92.0
• 5.92.0-beta003

You can reproduct this issue with this project on the branch feature/conversion

Steps:

1. Clone the repo on branch feature/conversion
2. Run .paket/paket.exe install
3. cd docs
4. dotnet restore

Also, when I was building the libs to use netstandard2.0 as fsproj format and TargetFramework it's was working as expected.

Reproduce the failure by running .paket/paket.exe install, then dotnet restore from docs for Docs.fsproj and inspect the generated obj files named in the report. Compare the ProjectReference entries in Docs.fsproj with the paket-generated restore outputs for Fulma.fsproj and Fulma.Extensions.fsproj. Done means the documented project structure restores without the duplicate (Fulma, 0.2.0-beta-002) key error.