Confused by documentation about header-only libs

The [documentation about packaging header-only libraries](https://docs.conan.io/en/latest/howtos/header_only.html) states:

> Note that this recipe has no other dependencies, settings or options. If it had any of those, it would be very convenient to add the package_id() method, to ensure that only one package with always the same ID is created, irrespective of the configurations and dependencies:
>
> def package_id(self):
> self.info.header_only()

I'm confused by that because if I understand the statement correctly, you should specify the ``package_id`` like that to prevent multiple packages if you have dependencies, settings, or options.

**Wouldn't that lead to the options of the package essentially being ignored and only one package existing that is just using the options specified in the last build?**

That's what's happening in my case when I use that ``package_id`` definitions. The second package creation step overwrites the first one because the package ID is identical:

$ conan create . -o with_license=True fschoenm/testing
Exporting package recipe
catch/2.9.1@fschoenm/testing: A new conanfile.py version was exported
catch/2.9.1@fschoenm/testing: Folder: /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/export
catch/2.9.1@fschoenm/testing: Package recipe modified in export, forcing source folder removal
catch/2.9.1@fschoenm/testing: Use the --keep-source, -k option to skip it
Configuration:
[settings]
arch=x86_64
arch_build=x86_64
build_type=Debug
compiler=gcc
compiler.libcxx=libstdc++11
compiler.version=8
os=Linux
os_build=Linux
[options]
with_license=True
[build_requires]
[env]
CC=gcc-8
CXX=g++-8
catch/2.9.1@fschoenm/testing: Forced build from source
Installing package: catch/2.9.1@fschoenm/testing
Requirements
catch/2.9.1@fschoenm/testing from local cache - Cache
Python requires
LicenseHelper/1.0@vsdk/stable
Packages
catch/2.9.1@fschoenm/testing:5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9 - Build

catch/2.9.1@fschoenm/testing: Configuring sources in /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/source
[==================================================] 612.7KB/612.7KB
[==================================================] 1.3KB/770B
catch/2.9.1@fschoenm/testing: Copying sources to build folder
catch/2.9.1@fschoenm/testing: Building your package in /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/build/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
catch/2.9.1@fschoenm/testing: Generator txt created conanbuildinfo.txt
catch/2.9.1@fschoenm/testing: Calling build()
catch/2.9.1@fschoenm/testing: WARN: This conanfile has no build step
catch/2.9.1@fschoenm/testing: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' built
catch/2.9.1@fschoenm/testing: Build folder /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/build/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
catch/2.9.1@fschoenm/testing: Generated conaninfo.txt
catch/2.9.1@fschoenm/testing: Generated conanbuildinfo.txt
catch/2.9.1@fschoenm/testing: Generating the package
catch/2.9.1@fschoenm/testing: Package folder /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
catch/2.9.1@fschoenm/testing: Calling package()
catch/2.9.1@fschoenm/testing package(): Packaged 1 '.hpp' file: catch.hpp
catch/2.9.1@fschoenm/testing package(): Packaged 1 '.lic' file: catch.lic
catch/2.9.1@fschoenm/testing: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' created
catch/2.9.1@fschoenm/testing: Created package revision 1aad708e20c9992bcc855b82cb1f46d5
$ conan create . -o with_license=False fschoenm/testing
xporting package recipe
catch/2.9.1@fschoenm/testing: The stored package has not changed
Configuration:
[settings]
arch=x86_64
arch_build=x86_64
build_type=Debug
compiler=gcc
compiler.libcxx=libstdc++11
compiler.version=8
os=Linux
os_build=Linux
[options]
with_license=False
[build_requires]
[env]
CC=gcc-8
CXX=g++-8
catch/2.9.1@fschoenm/testing: Forced build from source
Installing package: catch/2.9.1@fschoenm/testing
Requirements
catch/2.9.1@fschoenm/testing from local cache - Cache
Python requires
LicenseHelper/1.0@vsdk/stable
Packages
catch/2.9.1@fschoenm/testing:5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9 - Build

catch/2.9.1@fschoenm/testing: Copying sources to build folder
catch/2.9.1@fschoenm/testing: Building your package in /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/build/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
catch/2.9.1@fschoenm/testing: Generator txt created conanbuildinfo.txt
catch/2.9.1@fschoenm/testing: Calling build()
catch/2.9.1@fschoenm/testing: WARN: This conanfile has no build step
catch/2.9.1@fschoenm/testing: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' built
catch/2.9.1@fschoenm/testing: Build folder /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/build/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
catch/2.9.1@fschoenm/testing: Generated conaninfo.txt
catch/2.9.1@fschoenm/testing: Generated conanbuildinfo.txt
catch/2.9.1@fschoenm/testing: Generating the package
catch/2.9.1@fschoenm/testing: Package folder /home/fschoenm/.conan/data/catch/2.9.1/fschoenm/testing/package/5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9
catch/2.9.1@fschoenm/testing: Calling package()
catch/2.9.1@fschoenm/testing package(): Packaged 1 '.hpp' file: catch.hpp
catch/2.9.1@fschoenm/testing: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' created
catch/2.9.1@fschoenm/testing: Created package revision c95783ad4ceaa58fe00444fae5390e43

To help us debug your issue please explain:

- [x] I've read the [CONTRIBUTING guide](https://github.com/conan-io/conan/blob/develop/.github/CONTRIBUTING.md).
- [x] I've specified the Conan version, operating system version and any tool that can be relevant.
- [x] I've explained the steps to reproduce the error or the motivation/use case of the question/suggestion.