Building XCFramework gives "A library with the identifier 'ios-arm64' already exists."

I'm trying to build an XCFramework for our use of WebRTC and am using an Apple Silicon Mac (Mac Studio). I've downloaded the WebRTC stuff from Google and installed all their tools and used their tools to generate an Xcode project version. I can run Xcode and build a framework library. I've set the "arch" in Xcode to be the $ARCHS_STANDARD plus x86_64 (for simulator use by our developers still using Intel based Macs)

Using the documentation at https://developer.apple.com/documentation/xcode/creating-a-multi-platform-binary-framework-bundle I create an archive for iOS and one for iOS Simulator

% xcodebuild archive -project all.xcodeproj -scheme framework_objc_signed_bundle -destination "generic/platform=iOS" -archivePath "archives/WebRTC"

% xcodebuild archive -project all.xcodeproj -scheme framework_objc_signed_bundle -destination "generic/platform=iOS Simulator" -archivePath "archives/WebRTC_simulator" ONLY_ACTIVE_ARCH=NO SKIP_INSTALL=NO BUILD_LIBRARY_FOR_DISTRIBUTION=YES

First issue is it doesn't seem to create an X86 version for simulator based on running "% lipo -archs" on the actual binary library in the WebRT_simulator.framework, which only shows "arm64", though I don't know if that is valid.

Then when I try and create the XCFramework using

% xcodebuild -create-xcframework -archive archives/WebRTC.xcarchive -framework WebRTC.framework -archive archives/WebRTC_simulator.xcarchive -framework WebRTC.framework -output WebRTC.xcframework

I end up with this: A library with the identifier 'ios-arm64' already exists.

I found a post asking about this result but unfortunately it linked to another post for an answer and that post no longer exists.

What am I doing wrong and how can I go about creating the WebRTC XCFramework that runs on device, and both architectures simulators? Following the Apple docs ends up with an error that I don't understand.