Why do Jedi do this?

[Tinkerpeach]

Whenever they see an extra lightsaber laying around they always pick it up and dual wield it.

So if that's the better technique then why don't they just carry two to begin with?

 

[LurchAddams]

I have a question about Star Trek. Why do people even enter the holodeck anymore? It always ends in disaster!

 

[Jade Dragon]

There are many types of lightsaber combat. Only a few will dual-wield.

https://screenrant.com/star-wars-lightsaber-combat-forms-jedi-explained/#form-i-shii-cho

 

[T. A. Gardner]

Whenever they see an extra lightsaber laying around they always pick it up and dual wield it.

So if that's the better technique then why don't they just carry two to begin with?

Because it's in the script!