Diablo 2 pvp games, there is always those nerds that go out of there way to download that sandbox program to run 5 different diablo 2 windows, with 5 different accounts and characters. One player will have 5 chars of his in one game all to buff his amazon or hammerdin/charger. So he has bo barb, enchant sorc, paladin for fanaticism and druid for sage plus his amazon. So he is wasting 4 char slots in pvp game. I hope Diablo 2 resurrect could fix that problem of characters receiving excessive buffs from other chars or at least cant receive more that 1 charactor buff at a time. If you don’t fix it in Diablo 2 resurrected it will be worse then diablo 2 lod.
The problem is not with the game.
The problem is it’s players.
PvP has it’s own communities, many communities with rules.
Find one that plays by the rules you desire.
Or make a community with the rules you desire.
What you’re asking to be fixed, isn’t broken and is a fundamental part of multiplayer, even single player characters can have 5 - 6 auras and multiple pets and a spirit.
^ This. !00% that.
The problem can be fixed for diablo 2 resurrected. You are basically saying trust the community to do the right thing, the problem is the bad apples in the community exploit a flaw which can be fix! Dont tell you me support that exploit. If you do support it than you must be that bad apple that ruins the pvp aspect of the game. Who the hell wants to run 5 different d2 windows to have a fair chance against these exploiters? Just an FYI I have been a part of the d2 pvp comunnity for 20 years. We all think about this subject the same way.
It’s definitely an interesting problem.
Exploiting it the way you say with multiboxing definitely is a problem, however how to do it so that it doesn’t effect legitimate players would probably take some creative solutions.
I have played D2 off and on for 20 years and dabbled in PvP, was aware of lld and vlld leagues etc but never got super hardcore into it. I do seem to remember team games were a thing sometimes though, and it could be very fun.
So how does the game distinguish between a legitimate say 4v4 match where party members are buffing each other, and someone who is just running multiple instances to buff themselves for 1v1 duels?
Additionally if you’re doing PvM and someone comes in to PK the group, bring able to retain party buffs seems like something that you would want to have.
So simply restricting buffs period or only when hostiled doesn’t seem like a good solution in my opinion.
Maybe a game mode selection for PvP with options like ffa/melee that wouldn’t allow parties at all, 4v4 that would, etc so you could join PvP games based on what you wanted to do?
Those are some interesting points that you make and I am glad you asked. I can come up with a few solutions for these problems, but I would hope to attract the developers attention to this issue. It has ruined the amount of people in the pvp community over the years. Why pvp if we do not have a chance against a select few players that join with there 4-5 chars on there single computer, buff up from there off chars and wipe the game of players. We are having fun then he or she joins and does the mass buff exploit and kills then naked kills over and over. I sure know I stopped playing for a while off and on for years because of that very problem. I have had a lot of discussions with a lot of pvp players over the years in game and its very frustrating to us.
Possible solution
I have been thinking about this for some time. I think upon making a game you should be able to make 1 of 2 choices.
#1 would be Player vs Monster mode, so basically you would in game have an option to opt in or out for pvp and be able to hostile or be hostiled by anyone that joins.
#2 make a Player vs Player game and upon being hostiled or hostiling someone you automatically lose any buffs that are not self inflicted from you or any of your items in stash. Hostiling from character A to character B would be instant but after the first hostile on that very character there would be 1-3 minute timer until next hostile, So they just dont spam unhostile/hostile to wipe your buffs incase it is a team base pvp game.
That is a possible solution and I wouldn’t know how hard that would be to code that into there game but it is certainly worth an effort for the sake of pvp.
So wouldn’t your option 2 still prevent a 4v4 game where legitimate separate players are forming a team and want to share buffs within the team? Maybe this just isn’t a real scenario among the serious duelers so you’re not worried about it?
Simple solution. Don’t duel them. Nobody is forcing you to stay in 1 game. Ever notice these people buffing themselves are alone for hours throughout the day?
Then leave that game and play with (or against) other people who don’t bm 
how do you not discriminate against multiple different people playing over the same IP?
simple example: family 2 pcs
1 internet connection, 2 kids playing the same game with different accounts etc? but wanna play together?
I doubt Blizzard will fix that issue, since it’ll lead to increased sales. That player using all those characters has to have a different account for each character, which means he/she bought multiple copies of the game. Even if they banned this kind of player at the end of a season, odds are they’ll have a huge sale on D2:R before the start of the next season to get those players back in on the action again.
This is the pattern that occurred with D3 for the last several years. Ban players using an exploit at the end of season, then place the game on a sale to get more units moved so the stock holders are all 
at seeing those sale numbers soar.
It’s not an issue caused by the game, it’s an issue caused by the players that are abusing a mechanic for players to share buffs among themselves. Solutions have been listed for you, and odds are more likely you’ll be using one of those solutions before Blizzard listens to your suggestion.