Why do my friends get my voided villagers?

[Sudsofsplash]

I let my villager Walker leave, thus he went into the void, to never be seen again (I thought LOL) and then the very next day one of my friends says that her plot is sold and it's Walker who brought it? And when he moved in and he spoke to her, he remember her from my island!

I also had gotten Cube, who my other friend had actually sold to another player, but when Cube moved into my plot he actually said he was from my friend's town (But he was sold to another person???)

I remember something like this happening to my older sister in New Leaf, Benjamin had left my town Bubble and moved into hers and mentioned to her that he was from Bubble.

Is it just a coincidence, or is it more likely for friends to get your voided villagers?

 

[Mairen]

This is what is called your "void". When villagers move without someone inviting them to their town, they don't necessarily just disappear they go into your void. You can only have one villager in your void at a time. If you visit someone, or someone visits you, while you have someone in your void, and if they have an open plot, that villager will indeed move into their town.

Someone may be able to explain this better, but that's my understanding of this process

 

[Sudsofsplash]

This is what is called your "void". When villagers move without someone inviting them to their town, they don't necessarily just disappear they go into your void. You can only have one villager in your void at a time. If you visit someone, or someone visits you, while you have someone in your void, and if they have an open plot, that villager will indeed move into their town.

Someone may be able to explain this better, but that's my understanding of this process

That would make sense, however when she got Walker, she hadn't visited me since I voided him! And same with how I received my friends Cube (Also Cube had been traded, not voided I thought that was different)

 

[FraudulentDimetrodon]

You can only have one villager in your void at a time.

Everything else you said was good, but as far as I know, villagers can stack in the void if the void isn't cleared (though only one villager should be able to be passed onto another town at a time). That being said, the void in NH has a ton of glitches this time around and we can't really say how it's supposed to work and how similar it is to NL. For example, in NH, I've heard that you might not need an empty plot at the time of a visit/host to receive a voided villager, and that villager could move in the moment you put down a plot. Speaking of glitches...

I also had gotten Cube, who my other friend had actually sold to another player, but when Cube moved into my plot he actually said he was from my friend's town (But he was sold to another person???)

... this is actually one of the glitches regarding the void in NH. You can read more in this doc here (note that this doc isn't up-to-date and contains some things that may not be entirely accurate, like mentioning that the void can be cleared as in-game time passes). But essentially, any villager in boxes is copied to the void and villagers aren't cleared from the void properly. So even if a villager is directly adopted, those copies of the voided villager can be passed on to another town when hosting/visiting. Those copies also have a tendency to glitch.