• I have read CONTRIBUTING and have done my best to follow them.

What did you do?

Starting with a basic SPM project using the following Package.swift file:

// swift-tools-version: 5.9
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "QuickError",
    platforms: [.macOS(.v13)],
    products: [
        .executable(
            name: "QuickError",
            targets: ["quick-error"]),
    ],
    dependencies: [
        // Dependencies declare other packages that this package depends on.
        .package(url: "https://github.com/Quick/Quick.git", exact: "7.6.0"),
    ],
    targets: [
        .executableTarget(
            name: "quick-error"
        ),
    ]
)

Then I try to build a release binary for multiple architectures:

swift build -c release --build-path .build --arch arm64 --arch x86_64

What did you expect to happen?

Build to succeed as normal (works on Quick v7.5.0 and below).

What actually happened instead?

Build fails with the error

error: duplicate key found: 'ID(moduleName: "QuickLint", packageIdentity: quick, buildTriple: PackageGraph.BuildTriple.destination)'

Build works fine with individual architectures.

Environment

List the software versions you're using:

• Quick: 7.6.0+
• Nimble: 13.7.1
• Xcode Version: 16.0 (16A242d)
• Swift Version: Xcode Default

Please also mention which package manager you used and its version. Delete the
other package managers in this list:

• Swift Package Manager 6.0.0-dev

Project that demonstrates the issue

PackageTest.zip
(Package.swift file shared above, otherwise an empty project.)