How to use slot_was_set condition for and-ing and checking slots being set in stories?

Rasa Open Source
1

Example1

- slot_was_set:
  - product : x
- slot_was_set:
  - product : rasa

Example2

- slot_was_set:
  - product : x
  - product : rasa

Example3

- slot_was_set:
  - slot_1 : x
  - slot_2 : rasa

Example4

- slot_was_set:
  - slot_1 : x
- slot_was_set:
  - slot_2 : rasa

Which one of these is a correct approach and what does it do if it is correct?