How did 1e differ from 2e when it comes to dual wielding? In 2e you have a penalty to hit for all attacks (-2/-4) which was offset by your dexterity reaction adjustment, and the second weapon had to be smaller than your primary weapon or a dagger. I know later supplements also helped offset the penalties. You still had to trade in defence for offence, more significant once magical shields turned up at later levels.
2e is explicitly only one extra attack a round.
1e does not clearly say in its attacking with two weapon section whether it is one extra attack or an extra attack in an attack routine that gets multiplied by fighter bonus attacks and haste. There is a reference though in the initiative section to using plural weapons as part of an attack routine that is multiplied for high level fighters and haste purposes.
2e PH page 127:
Attacking with Two Weapons
A tricky fighting style available only to warriors and rogues is that of fighting with two weapons simultaneously. The character chooses not to use a shield in favor of another weapon, granting him a greater number of attacks, with a penalty to his attack rolls (rangers are exempt from the attack roll penalty).
When using a second weapon in his off-hand, a character is limited in his weapon choice. His principal weapon can be whatever he chooses, provided it can be wielded with one hand. The second weapon must be smaller in size and weight than the character’s main weapon (though a dagger can always be used as a second weapon, even if the primary weapon is also a dagger). A fighter can use a long sword and a short sword, or a long sword and a dagger, but he cannot use two long swords. Nor can the character use a shield, unless it is kept strapped onto his back.
When attacking, all characters but rangers suffer penalties to their attack rolls. Attacks made with the main weapon suffer a –2 penalty, and attacks made with the second weapon suffer a –4 penalty. The character’s Reaction Adjustment (based on his Dexterity, see Table 2) modifies this penalty. A low Dexterity score will worsen the character’s chance to hit with each attack. A high Dexterity can negate this particular penalty, although it cannot result in a positive modifier on the attack rolls for either weapon (i.e., the Reaction Adjustment can, at best, raise the attack roll penalties to 0).
The use of two weapons enables the character to make one additional attack each combat round, with the second weapon. The character gains only one additional attack each round, regardless of the number of attacks he may normally be allowed. Thus, a warrior able to attack 3/2 (once in the first round and twice in the second) can attack 5/2 (twice in the first round and three times in the second).
1e DMG page 70:
Attacks With Two Weapons:
Characters normally using a single weapon may choose to use one in each hand (possibly discarding the option of using a shield). The second weapon must be either a dagger or hand axe. Employment of a second weapon is always at a penalty. The use of a second weapon causes the character to attack with his or her primary weapon at –2 and the secondary weapon at –4. If the user’s dexterity is below 6, the Reaction/Attacking Adjustment penalties shown in the PLAYERS HANDBOOK are added to EACH weapon attack. If the user’s dexterity is above 15, there is a downward adjustment in the weapon penalties as shown, although this never gives a positive (bonus) rating to such attacks, so that at 16 dexterity the secondary/primary penalty is –3/–1, at 17 –2/0, and at 18 –1/0.
The secondary weapon does not act as a shield or parrying device in any event.
DMG Page 62:
Initiative For Creatures With Multiple Attack Routines: When one or more creatures involved in combat are permitted to use their attack routines twice or more often during the round, then the following initiative determinants are employed. When the attack routine may be used twice, then allow the side with this advantage to attack FIRST and LAST with those members of its group who have this advantage. If it is possessed by both parties, the initiative roll determines which group strikes FIRST and THIRD, which group strikes SECOND and LAST. If one or both groups have members allowed only one attack routine, it will always fall in the middle of the other attacks, the order determined by dicing for initiative, when necessary. If one party has the ability to employ its attack routines thrice, then the other party dices for initiative to see if it, or the multi-routine group, strikes first in the mid-point of the round. Extrapolate for routines which occur four or more times in a round by following the method above.
Note that a routine is the attack or attacks usual to the creature concerned, i.e. a weapon (or weapons) for a character, a claw/claw/bite routine for a bear (with incidental damage assessed as it occurs — the hug, for example). A 12th level fighter is allowed attack routines twice in every odd numbered melee round, for example, and this moves up to three per round if a haste spell is cast upon the fighter. Damage from successful attacks is assessed when the “to hit” score is made and damage determined, the creature so taking damage having to survive it in order to follow its attack routine.