I found online some guides, referring to people who have more than one copies of the game (i have two). Battlenet is great, if you can find people to play with or friends from way back (i got unlucky with both). I am a very skilled player, but it is common knowledge that the more people in a game, the more the XP for everyone, as well better DROPS! My problem is always that, occasional rare and usually crappy drops! I have many possibilities to choose from, like:

1) Dual install on same pc for simultaneous play of two characters online from same machine.
2) Install both games in two different pcs in house, park one character move the other.

Etc. But i also noticed one thing. Adding the retail copy's key on a battlenet account, generates a NEW game key, totally different from that of the physical disc's. Which left me with FOUR keys in total. I need to ask; if i find 3 more pcs other than my laptop, install to all of them the game using one CD-KEY for each machine, will i be able to put simultaneously FOUR accounts/players online at the same time? Or does the one Battlenet key counts as being the same with the retail one redeemed?

I don't want to cheat! My only intention is to PARK characters inactive while i farm xp (to get much more) and to party with level one characters, so the drops from bosses are better (common knowledge that when you beat a boss before their quest is completed already, drops are MUCH better). In nightmare, i could get the all goodies i once used to find, this way, easily. (So i could enter hell fully armed and prepared).

Anyone tried or knows for sure if such a thing is feasible?

Use this. :)

Seeing as how the goal is to farm items and XP doesn't matter no? I find using players8 to be a great way to test builds.

Indeed, it is great! And especially with a high magic find equipment, it works wonders!

I guess both of you don't have melee builds ;P
The sorceress was super fast even at P8, but my poor paladin struggled at P3 lol (and I had various high uniques).

Or maybe useful runewords are wayyy easier to create in MP.

You guessed right. I never used melee in diablo 2. I was melee in good old diablo 1 + hellfire era only, with the warrior.