Must I two-weapon fight with different weapon types or can they be matching?

Question

I think I'm clear on two-weapon fighting (thanks to Two-Weapon Fighting & Bonus Action in 5e) except for one thing. The PHB says (p. 195):

When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand. [emphasis mine]

Does a "different" weapon mean a different type of weapon, or just a different physical instance of a weapon? In other words, can I fight with two shortswords (one in each hand), or would I have to use a dagger or some other type of light weapon in my off hand?

Answer 1

Just a different instance of a weapon

Weapons can be of the same type (ie two short swords), but you must have two actual weapons to use two weapon fighting.

The wording is only there to prevent someone from trying to use two-weapon fighting with one weapon.

The dual-wielder feat does supply circumstantial evidence for this when it says:

You can use two-weapon fighting even when the one handed melee weapons you are wielding aren’t light.

But really it is just common sense in this case. The wording would have been much more specific (perhaps "...with a light melee weapon with a different name") if the kind of restriction you propose was the intended reading.

Answer 2

The latter, you may dual-wield the same type of weapon (say, two +2 shortswords), but can't have the same weapon moving between hands.

As proof, other than common sense (dual-wielding the same weapon is fairly common in my experience), the Dual Wielder feat's first property's wording makes it much clearer (PHB, p. 165, italics mine):

Dual Wielder

You master fighting with two weapons, gaining the following benefits:

• You gain a +1 bonus to AC while you are wielding a separate melee weapon in each hand.
• You can use two-weapon fighting even when the one handed melee weapons you are wielding aren’t light.
• You can draw or stow two one-handed weapons when you would normally be able to draw or stow only one.

Answer 3

The two weapons can be the same type, or different types.

"Different" just means "not the same". It doesn't mention anything about type; it's simply clarifying that you can't hold just one weapon and attack with it again as a bonus action. You need to be holding two light one-handed melee weapons when you make the initial qualifying attack as part of the Attack action. Those two weapons can be shortswords, daggers, handaxes, or any other qualifying weapons, or any combination thereof, but there need to be two weapons.