Hi Dod,
Yes, whichever method you use, one MediaRecorder element means one audio file, containing the most recent recording — you should try it out yourself though to double-check. Zip files containing recordings have non-related, unique filenames and may contain one or more recordings (because trials can contain several MediaRecorder elements, and uploads can take place after several trials too) but the audio files in the zip files are indeed named after the name of the MediaRecorder
Jeremy