We have been happily using system.data.sqlite in a project for a while. Our application is published as a single file (which bundles all of the executable and DLL files into aaa single runtime for user convenience).  We recently went through an update cycle Increasing the version of the tooling and various libraries and started getting warnings about the library

## Steps to reproduce

* Create a core application e.g. `dotnet new console -lang F#`
* Add the SQLite library  e.g. ` dotnet add package System.Data.SQLite.Core --version
* Edit the project file to publish to a single file. For clarity the full example project file is included below
* attempt to publish `dotnet publish`

```
<Project Sdk="Microsoft.NET.Sdk">

 <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <PublishTrimmed>true</PublishTrimmed>
    <PublishSingleFile>true</PublishSingleFile>
    <RuntimeIdentifier>win-x64</RuntimeIdentifier>
  </PropertyGroup>

  <ItemGroup>
    <Compile Include="Program.fs" />
  </ItemGroup>

  <ItemGroup>
    <PackageReference Include="System.Data.SQLite.Core" />
  </ItemGroup>

</Project>
```

## Publish

The publishing process fails (here I am using 3.1.201) Because the relative bundle paths contained inside the nuget package are both the same for net standard 2.0 and net standard 2.1. The bundling process can't copy both of them into the same location and so it fails.

```
$ dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   3.1.201
 Commit:    b1768b4ae7

```
```
$ dotnet publish
Microsoft (R) Build Engine version 16.5.0+d4cbfca49 for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 200.73 ms for
  Playground3 ->
  Optimizing assemblies for size, which may change the behavior of the app. Be sure to test after publishing. See:
C:\Program error MSB4018: The "GenerateBundle" task failed unexpectedly.
C:\Program error MSB4018: System.ArgumentException: Invalid input specification: Found multiple entries with the same BundleRelativePath
C:\Program error MSB4018:    at Microsoft.NET.HostModel.Bundle.Bundler.GenerateBundle(IReadOnlyList`1 fileSpecs)
C:\Program error MSB4018:    at Microsoft.NET.Build.Tasks.GenerateBundle.ExecuteCore()
C:\Program error MSB4018:    at Microsoft.NET.Build.Tasks.TaskBase.Execute()
C:\Program error MSB4018:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
C:\Program error MSB4018:    at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask)

```


Running the publishing process in diagnostic mode you can see the issue `dotnet publish -v diag` - netstandard2.0 and netstandard2.1 libs both try to publish to the same relative path, upsetting the publisher.  I think the fix is to either publish them to different paths, or perhaps to avoid bundling both versions of netstandard in one package.  The paket tool also provides this warning when working through dependencies

```
Could detect native library in which is incorrectly packaged because it should be directly under 'native' or in the 'nativeassets' folder, please tell the package author
```

The impact of this is that it seems impossible with latest dotnet core tooling to publish a single file if this library is used.  Not sure what we can do to work around, but probably hacking the nuget package for now.


```

                                   AssetType=native
                                   CopyLocal=true
                                   CopyToPublishDirectory=PreserveNewest
                                   DestinationSubPath=SQLite.Interop.dll
                                   NuGetPackageId=System.Data.SQLite.Core

                                   PackageName=System.Data.SQLite.Core


                                   RelativePath=SQLite.Interop.dll  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

                                   AssetType=native
                                   CopyLocal=true
                                   CopyToPublishDirectory=PreserveNewest
                                   DestinationSubPath=SQLite.Interop.dll
                                   NuGetPackageId=System.Data.SQLite.Core

                                   PackageName=System.Data.SQLite.Core


                                   RelativePath=SQLite.Interop.dll   <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<


```