You can use the same Update Module type for all. Note that ${FILES}/current_artifact_name lists the currently installed artifact. The one you are looking for is ${FILES}/header/artifact_name, which lists the name in the artifact being installed (see this section for more info).
However, I think for robustness purposes I would consider putting the information about which microcontroller the update belongs to, somewhere else. Either an extra payload file in the artifact (mender-artifact -f option), or perhaps in the meta-data (mender-artifact -m option), which is freeform JSON that the Update Module can use for any purpose. Artifact name is, well, exactly that, just a name, and is not meant to carry architecture details.