Steam – Does MW3 let more than one person play over LAN with one copy of the disc

I only have access to the Xbox 360 version of the game but here are some of the options that you can set up.

• Pick any of the maps
• The standard game types of: FFA, TDM, S&D, sabotage, domination, headquarters, CTF, demolition, kill confirmed, and team defender
• And alternate modes of: drop zone, team juggernaut, juggernaut, gun game, infection, and one in the chamber
• Enable custom game options such as number of lives, create customized default classes, turn off the kill cam, turn off killstreaks, etc.
• You can create custom default classes and assign them to each team.
• You can also allow custom classes, but restrict choices. This means you can turn off individual guns, entire gun classes (assault, smg, lmg, etc), turn off perks, etc.

Yes, MW3 will support LAN play.

Infinity Ward creative strategist, Robert Bowling has been answering questions on Twitter in the aftermath of the Call of Duty XP event that happened over the course of the weekend. Dedicated Servers for Modern Warfare 3 have already been confirmed, but Bowling also mentions that LAN play will be possible, which certainly wasn’t a given, considering how Modern Warfare 3 will tie in heavily with Activision’s online Call of Duty Elite service.

“Yes, #MW3 has LAN,” Bowling tweets, “along with detailed class restriction control + default class creation option.”

The class restriction control will give LAN gamers the ability to “restrict any weapon, equipment, perk, deathstreak, secondary, attachment, ANYTHING from being used when setting up game,” Bowling adds.

Source: PCGamer

You cannot log onto the same Steam account in multiple places or it will kick other computers off. Additionally, I think you are unable to 'double buy' a game (though if you got the same game different ways—in a pack and a la carte, for example—you might) on the same account unless it's a gift.

However, you may be able to launch Battlefield outside of Steam (look in the steamapps folder for the executable) however, and work from there. As you suggest, playing online with the same copy may not work, but a LAN game may. Using one copy on multiple computers simultaneously is a little grey though.