How to distinguish between the "se" in "V-se" and "se" in "cómo se (uno) va"? And how to use them both in one sentence?

Question

"Se" can be used as impersonal, as a substitute for "uno"

cómo se va a la plaza?

And "se" can be used as a part of a verb, for instance:

se fue él

Questions:

1. How to distinguish between them?

And also

2. How do I use them both in one sentence?

For instance:

 cómo se [uno] se marcha [marcharse] a Roma?

Next to each other?

Answer 1

1) How to distinguish between them?

When "se" is an impersonal pronoun, there is no subject:

• Se va a la plaza cruzando la avenida. (You go/One goes to the square by crossing the avenue.)

When "se" is used for the verb to be pronominal (in which case "irse" means "leave"), there needs to be a subject:

• ¿Cómo se va uno de una fiesta cuando no está cómodo? (How does one leave a party when one doesn't feel at ease?)

2) How do I use them both in one sentence? (Good question!)

There is no overlapping of se's. You need to use a subject, either express (uno) or tacit (tú):

• ¿Cómo se va uno de una fiesta cuando no está cómodo? (translated above)

• ¿Cómo te vas de una fiesta cuando no estás cómodo? (How do you leave a party when you don't feel at ease?)

Summing up:

1. Impersonal use:

   • Se va a la plaza por aquí. (= Uno va a la plaza por aquí / (Tú) Vas a la plaza por aquí.)

2. Pronominal use:

   • Se va del trabajo lo más temprano posible. (He leaves work as early as possible.)

3. Impersonal use + Pronominal use:

In this case, pronominal "se" has preeminence over impersonal "se" (we cannot say "se se"). If both meanings need to be conveyed, "se" is pronominal and "uno" or the second person -- with "te" for pronominal meaning in agreement with "tú" -- is used to make the sentence impersonal:

• Uno se va del trabajo lo más temprano posible. (One leaves work as early as possible.)

• (Tú) Te vas del trabajo lo más temprano posible. (You leave work as early as possible.)