Rider shows duplicate file entries under project

[NatElkins]

Example:

But the project file looks like:

Steps to repro:

1. dotnet new -i Fabulous.XamarinForms.Templates
2. dotnet new fabulous-xf-app -n SqueakyApp
3. Open SqueakyApp.sln with Rider.
4. Look at the netstandard2.0 F# project.

Expected behavior:

One file is shown.

Actual behavior:

Two files are shown.

About Rider:

JetBrains Rider 2020.2.1
Build #RD-202.6397.268, built on August 20, 2020
Licensed to Masse / Nathaniel Elkins
Subscription is active until September 25, 2020
Runtime version: 11.0.7+10-b944.20 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
.NET Framework 4.0.30319.42000
Windows 10 10.0
GC: ParNew, ConcurrentMarkSweep
Memory: 1450M
Cores: 8
Registry: debugger.new.debug.tool.window.view=true, ide.tree.horizontal.default.autoscrolling=false, performance.watcher.sampling.interval.ms=200, ide.borderless.tab.caption.in.title=false, ide.tooltip.showAllSeverities=true, show.diff.preview.as.editor.tab=true, light.edit.file.open.enabled=false, performance.watcher.unresponsive.interval.ms=1000, search.everywhere.settings=true, show.diff.preview.as.editor.tab.with.single.click=true, parameter.info.max.visible.rows=10, ide.win.file.chooser.native=true, vcs.log.show.diff.preview.as.editor.tab=true, search.everywhere.pattern.checking=false, ide.tooltip.initialDelay=0, ide.require.transaction.for.model.changes=false, ide.debug.in.title=true, rdclient.asyncActions=false
Non-Bundled Plugins: IdeaVIM, com.microsoft.vso.idea, com.jetbrains.rider.android

[NatElkins]

Curiously after I installed Visual Studio and the Xamarin workload it doesn't show that issue anymore. In general the Xamarin installation process that Rider took me through didn't seem to install things properly.

[auduchinok]

This happens when selected MSBuild doesn't have F# targets. Installing VS/Xamarin installed needed things, so it's expected. Is there any chance you could reproduce it again so it'd be possible to know what MSBuild was used before installing VS/Xamarin?