That’s bizarre… no clue why it’s doing that. I’d first check to see if the underlying AMP install is working as expected. I’ve got the instructions to do so manually laid out here; just swap the data.type argument to push, announce, or tts to match what’s sending the extra notifications.
It seems this blueprint, at least under the latest HASSIO release, doesn't allow the settings to be saved. I can run the actions no problem from within the settings of the script, but the script has no way to save the settings. I can save a new script using the blueprint, but it only ever shows the blueprint page, which doesn't allow for any inputs. I can select the 3 dots / Settings / (<) back arrow, which then gets me to the place where I can select devices and type and select a message, but I can only Run the script, not save it.