Change date autoresponder settings will cause double e-mailing?

Change date autoresponder settings will cause double e-mailing?

Hi, 

I want to change the sending date of my autoresponder from 4 days to 6 days. When i am going to change this, does this mean the people that subscribe the mailing list on 15-7-2016, will receive the same e-mail on 19th july and also on 21th of july? Or are those contacts automatically filtered out? 

Kind regards.