How to support multiple package versions in CMake's user package registry? - cmake

Question

I'm trying to understand how I can use the CMake user package registry to support multiple builds, for example a Debug and a Release build.
I have a package1, which properly calls export(PACKAGE package1) so it registers the build directory with CMake's user package registry. I then proceed to creating 2 separate build directories, one for Debug and one for Release (note that I made the version for the Debug build 3.0.2000000, while the version for the Release build is 3.0.1000000, because I wanted CMake to prefer the Debug build in my use case). As expected, each of these builds registered an item in the registry:
> ls ~/.cmake/packages/package1/
212e973d0f1858e4bdf95b9d105bed5a 78094ed9b729d420c3f782cd8e668e64
Now in a different project, package2, I use find_package(package1 3.0.740) but it only ever finds the one in the Release build. I tried inspecting the package1_CONSIDERED_CONFIGS and package1_CONSIDERED_VERSIONS right after calling find_package but again only the Release build's config and version are there.
The code in package2's CMakeLists.txt file:
SET(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
SET(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)
message("CMAKE_FIND_PACKAGE_SORT_ORDER="
"${CMAKE_FIND_PACKAGE_SORT_ORDER}")
message("CMAKE_FIND_PACKAGE_SORT_DIRECTION="
${CMAKE_FIND_PACKAGE_SORT_DIRECTION}")
find_package(package1 3.0.740)
message("Considered Configs: ${package1_CONSIDERED_CONFIGS}")
message("Considered Versions: ${package1_CONSIDERED_VERSIONS}")
Result of CMake running above code:
cmake ../..
-- Using link pool size - 16 jobs
CMAKE_FIND_PACKAGE_SORT_ORDER=NATURAL
CMAKE_FIND_PACKAGE_SORT_DIRECTION=DEC
Considered Configs: /path/to/package1/Release/package1Config.cmake
Considered Versions: 3.0.1000000
What am I doing wrong? How is the user registry supposed to be used?