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Issue Description:

Let's consider two projects:
MyFramework - which is a binary framework that has dependency on A (e.g. Alamofire).
MyApp - which is an app that has dependency on MyFramework and also on A (e.g. Alamofire).

MyFramework uses Swift Package Manager to add A as a dependency and it uses `@_implementationOnly` imports for A. Now we build this framework as a XCFramework and we add it as a dependency to MyApp. During runtime we receive following warnings about A:

`Class XXX is implemented in both X and Y. One of the two will be used. Which one is undefined.`

I assume that SPM should be statically linking A into MyFramework and there shouldn't be any warnings during runtime. Please see the attachments to reproduce this issue. MyFramework project contains a build script that was used to generate XCFramework.