Как два веб-сайта Flask объединяются вместе на сервере Ubuntu?

На страницах speech-dispatcher man:

DESCRIPTION
       speech-dispatcher  is  a  server process that is responsible for trans‐
       forming requests for text-to-speech output into actual speech  hearable
       in the speakers. It arbitrates concurrent speech requests based on mes‐
       sage priorities, and abstracts different  speech  synthesizers.  Client
       programs,  like  screen  readers  or  navigation  software, send speech
       requests to speech-dispatcher using TCP  protocol  (with  the  help  of
       client  libraries).  speech-dispatcher is usually started automatically
       by client libraries (i.e. autospawn), so you only need to run it  manu‐
       ally if testing/debugging, or when in other explicit need for a special
       setup.

Если вы уже не изменили свои системные настройки, spd должен быть запущен автоматически.