Re-run of cmake when configuring a Qt module for build fails when building for iOS.

Steps to reproduce on mac / bash:
0) Set up Qt6 iOS development environment
1) git clone git://code.qt.io/qt/qtscxml.git
2) mkdir build && cd build
3) qt-configure-module ../qtscxml // This should pass fine
4) qt-configure-module ../qtscxml

=> The qt_add_internal* cmake calls will result in lines similar to the one below:

CMake Error at /Users/juha.vuolle/qts/6/ios_dev_source/qtbase/cmake/QtTargetHelpers.cmake:156 (add_library):
  add_library cannot create ALIAS target "Qt6::Scxml" because another target
  with the same name already exists.
Call Stack (most recent call first):
  /Users/juha.vuolle/qts/6/ios_dev_source/qtbase/cmake/QtModuleHelpers.cmake:102 (qt_internal_add_target_aliases)
  src/scxml/CMakeLists.txt:6 (qt_internal_add_module)

Some additional details:

• The issue reproduces similarly if bypassing the qt-configure-module and invoking cmake directly.
• The issue can be worked around by deleting all previous build artifacts from the qt installation directory (eg. qtbase/... if using developer build).
• The issue reproduces on two repos I tried with: qtscxml and qtsensors.
• The issue does not happen when building for android / linux / windows / mac.