xkcd #3310: Rejected Space Mission Profiles
Title text:
Although NASA agreed that Voyager 2 'seemed lonely' they decided against launching a companion orbiter mission after further measurements indicated that the spacecraft actually preferred the peace and quiet.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3310/
Perhaps Voyager 3 as 2 happened already.
https://www.youtube.com/watch?v=qYNIsgDrIRE
Although you might need to slingshot of Jupiter and Saturn at the right time.
It amazes me how our greatest minds were able to work this out with the technology and understanding they had.