> Why are we choosing more than 1 action in SARSA? 

There is never a state where more than one action is chosen.

The appearance of two `Choose` statements is an artifact of the loop design and variable management in the pseudocode.

> One for going into the next state and the other one for updating the Q function?

Sort of. There is only ever *one* chosen action for each state.

However, you need to have two actions in scope - the current action (just taken and observed) and planned next action, in order to process the update rule. Hence there are two variables `a` and `a'` and the code needs to generate one or other outside the main loop, or have some other way to ensure that it has access to current and next values.