Duplicate step argument transformations created for external assemblies

Duplicate step argument transformations created for external assemblies and causing false "Multiple step transformation matches to the input" warning

SpecFlow Version:

[X] 2.2
[ ] 2.1
[ ] 2.0
[ ] 1.9

Used Test Runner

[X ] SpecFlow+Runner
[ ] MSTest
[ ] NUnit
[ ] Xunit

Version number: 1.6.3

Visual Studio Version

[X] VS 2017
[X] VS 2015
[ ] VS 2013

Are the latest Visual Studio updates installed?

[X] Yes
[ ] No

.NET Framework:

[X] >= .NET 4
[ ] before .NET 4

Test Execution Method:

[X] Visual Studio Test Explorer
[ ] TFS/VSTS – Task – PLEASE SPECIFY THE NAME OF THE TASK
[ ] Command line – PLEASE SPECIFY THE FULL COMMAND LINE

<SpecFlow> Section in app.config

  <specFlow>
        <stepAssemblies>
            <stepAssembly assembly="CalculatorSteps" />
        </stepAssemblies>

        <!-- For additional details on SpecFlow configuration options see http://go.specflow.org/doc-config -->
        <!-- For additional details on SpecFlow configuration options see http://go.specflow.org/doc-config -->
        <!-- use unit test provider SpecRun+NUnit or SpecRun+MsTest for being able to execute the tests with SpecRun and another provider -->
        <!-- For additional details on SpecFlow configuration options see http://go.specflow.org/doc-config -->
        <!-- use unit test provider SpecRun+NUnit or SpecRun+MsTest for being able to execute the tests with SpecRun and another provider -->
        <!-- For additional details on SpecFlow configuration options see http://go.specflow.org/doc-config --><!-- use unit test provider SpecRun+NUnit or SpecRun+MsTest for being able to execute the tests with SpecRun and another provider --><unitTestProvider name="SpecRun" />
        <plugins>
            <add name="SpecRun" />
        </plugins>
</specFlow>

Repro Project

https://github.com/jtdubya/SpecFlowTransformIssueExample

Issue Description

Duplicate step argument transformations are being created for steps in external assemblies which give the false "warning: Multiple step transformation matches to the input" in the output. The step argument transformations, identified by the [StepArgumentTransformation] annotation, that are referenced from external assemblies are duplicated in the binding registry.

Steps to Reproduce

Create step argument transformations is a separate project from the test project and reference them in the specflow>stepAssemblies section of the app.config

SpecFlowOSS / SpecFlow