Same version, new addon_id.
If you already have v1.0.0 installed, there is no need to upgrade. There is no new functionality in v1.0.0a. New installations should use this v1.0.0a version to ensure compatibility with future releases.
Due to the change in addon_id, upgrading from v1.0.0 to v1.0.0a is not supported - but there is no data stored with this addon, so simply uninstalling v1.0.0 before installing v1.0.0a will be sufficient.