Sharing one folder with multiple guest users

I am not sure if I did something wrong or what triggered this behaviour but let me describe what I did and what happened:

I selected one folder  > clicked share with users > add users > add guest user > added the name and email of user A > added the name and email of user B > adjusted the permissions of both to download only and clicked apply.

Furthermore, I then checked the emails which were sent out to see if they were properly sent and found two outgoing emails: 

Email a) was sent to user A and email b) was sent to user A AND user B both directly addressed in the TO: section. 

Now this is not a problem as I was sharing with both of them intentionally, and they are one team, but I suppose the emails to multiple people should not be sent out together, right? 

Here is what it looks like on Gmail as I use their SMTP server: