Is it still something people does? Is it still legal? Ty in advance

yeah u can

Lately blizzard has been changing their policies toward multiboxing. (especially in WoW)

Previously, it was basically allowed as long as you don't automate any of your inputs, like botting. (pressing one key and having a character do many actions that should require many keys to be pressed. Or have scripts play the game for you.)
And both software and hardware boxing, as long as you don't go over that line, were completely legal. So 1 to 1 software keycloning was allowed.

Now, they have started to come down on software boxing, which is kind of silly. As hardware boxing is something that can't be guarded against anyway, why try to crack down on software boxing if they don't actually do anything you can't do with hardware boxing?
Anyway, I am going to box D2R myself, and I'll be doing a combination of hardware and software boxing. Not sure if they'll ban me, will cross that bridge when I come to it. In any case, I box for fun and challenge, so I won't be automating anything and think I should be fine.

I used to software box in WoW back in TBC and WotLK.

If you go the full hardware route, you're always gonna be safe from bans, but that obviously might require more financially to set up. (Multiple PC's, hardware KVM switches and USB synchronizers)
Software boxing has always been the cheap route, but carries a little risk, as blizz can detect processes being run on your PC and you might get flagged for it.

As of yet though, I don't think they have taken any action to D3 boxing like they did with WoW and I am not sold on the fact that the WoW boxers that did get banned, were really boxing within the limits of what I mentioned earlier. The line between ' legit' software boxing and outright botting to gain an advantage is quite thin and easily crossed, especially when you work and are familiar with software that can do both.

This post was edited by FluffyWolf on Aug 15 2021 12:27am

As long as you are manually in control of all characters, shouldn't be an issue.

Is pressing one key and go through 3 games is manually control

If 1 key bind controls three characters at once, that’s not ok.

If your chars are all being played regularly, just more than 1 at a time that is ok.

Actually, that is their stance for World of Warcraft. They haven't added those new rules for other games.

As far as I know, for other games mirroring is still tolerated like it used to be in WoW, just no automation/botting.

edit: DISCLAIMER: Do so at your own risk though. The post that changed the rule on mirroring did specifically mention WoW, but who knows. I am no Blizz Employee so I can't say anything with certainty.

This post was edited by FluffyWolf on Aug 15 2021 11:24am

https://us.forums.blizzard.com/en/wow/t/policy-update-for-input-broadcasting-may-2021/956610

Software an hardware was banned but is wow specific nothing about d3 or d2r but i can see it spreading to d2r if they dont have game limitations because of static routes you can farm.

On November 3, 2020, we posted an update to our policy for input broadcasting software, and soon thereafter, we began taking action against accounts found to be using third party software to automatically mirror keystrokes to multiple game clients. We find that, like full automation of play, multiple-account mirroring disturbs the gameplay experience for the vast majority of players who control a single account at a time.

We will now additionally prohibit the use of all software and hardware mechanisms to mirror commands to multiple World of Warcraft accounts at the same time, or to automate or streamline multi-boxing in any way. Players found to be in violation of this policy are subject to account actions. These actions can include warnings, account suspensions and, if necessary, permanent closure of the player’s World of Warcraft account(s), as activities which effectively replicate automated gameplay are contrary to the terms and conditions of the Blizzard End-User License Agreement (EULA).

We urge all players to cease using any means of mirroring gameplay across multiple WoW accounts immediately, in order to maintain uninterrupted access to World of Warcraft.

Thank you for the replies it seem to affect wow

Those were the rules for Diablo 3 as well unless they have changed