As far as I can tell this is not explicitly stated in 1e.
I can not find a reference to any specific rules on two weapon fighting in the
1e PH.
In the
1e DMG on page 70 it has a section on two-weapon fighting but it only discusses attack penalties and what weapons can be used.
"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."
This leaves it ambiguous as to whether the offhand doubles all your weapon attacks, or doubles your base attack from one to two and other attacks double the offhand attack or not depending on their specifics.
I always felt doubling attacks was a natural inference, but doubling the base only is not an unreasonable inference which would mean other things that increase attacks would depend on their wording for whether they doubled the off hand attack or not or possibly more inferences when not explicit. Haste for example doubles attack rates.
Player's Handbook Page 105 says:
"The 1 minute melee round assumes much activity — rushes, retreats, feints, parries, checks, and so on. Once during this period each combatant has the opportunity to get a real blow in. Usually this is indicated by initiative, but sometimes other circumstances will prevail. High level fighters get multiple blows per round, so they will usually strike first and last in a round. Slowed creatures always strike last. Hasted/speeded creatures strike first. A solid formation of creatures with long weapons will strike opponents with shorter weapons first, a rushing opponent will be struck first by a pole arm/spear set in its path. Your DM will adjudicate such matters with common sense. When important single combats occur, then dexterities and weapons factors will be used to determine the order and number of strikes in a round."
I always inferred two weapon fighting is a special circumstance and the blows went off simultaneously, unlike a fighter's staggered multiple attacks. But having the offhand be a normal attack that can be in between a high-level fighter's multiple staggered attacks is not unreasonable.
PH page 105 also says:
"Monster Attack Damage:
Monsters with weapons will generally attack much as characters do. Those with natural weaponry such as claws, talons, teeth, fangs, tusks, horns, etc. will use the matrix for monster attacks. There are exceptions to both cases."
So this brings up drow in
G3 and the
Fiend Folio.
In the fiend folio the 2 HD drow get 1 or 2 attacks per round, presumably due to their two weapon fighting options.
G3: "They are also both intelligent and highly coordinated, being able to use either or both hands/arms for attack and defense."
FF: "Drow are also both highly intelligent and co-ordinated, being able to use either or both hands/arms for attack and defense."
In both cases they are said to be normally armed with short swords and long daggers, sometimes with maces.
Maximum of 9th level fighter in the Fiend Folio.
2 attacks at 2 HD is compatible either way.
Haste from the PH explicitly doubles attack rates.
"Haste (Alteration)
Level: 3 Components: V, S, M
Range: 6” Casting Time: 3 segments
Duration: 3 rounds + 1 round/level Saving Throw: None
Area of Effect: 4” × 4” area, 1
creature/level
Explanation/Description: When this spell is cast, affected creatures function at
double their normal movement and
attack rates. Thus, a creature moving at 6” and attacking 1 time per round would move at 12” and attack 2 times per round. Spell casting is not more rapid. The number of creatures which can be affected is equal to the level of experience of the magic-user, those creatures closest to the spell caster being affected in preference to those farther away, and all affected by haste must be in the designated area of effect. Note that this spell negates the effects of a slow spell (see hereafter). Additionally, this spell ages the recipients due to speeded metabolic processes. Its material component is a shaving of licorice root."
Page 25 of the PH provides the fighter extra attacks information.
FIGHTERS’, PALADINS’, & RANGERS’ ATTACKS PER MELEE ROUND TABLE
Level
Attacks per Melee Round*
Fighter 1-6
Paladin 1-6
Ranger 1-7
1/1 round
1/1 round
1/1 round
Fighter 7-12
Paladin 7-12
Ranger 8-14
3/2 rounds
3/2 rounds
3/2 rounds
Fighter 13 & up
Paladin 13 & up
Ranger 15 & up
2/1 round
2/1 round
2/1 round
*With any thrusting or striking weapon
Note: This excludes melee combat with monsters (q.v.) of less than one hit die (d8) and non-exceptional (0 level) humans and semi-humans, i.e. all creatures with less than one eight-sided hit die. All of these creatures entitle a fighter to attack once for each of his or her experience levels (See COMBAT)."
The combat section references these extra attacks with regard to initiative, but does not specifically provide information applicable to two weapon situations.