¿Un "se" o dos?

¿Un "se" o dos?
 

Si se usa un pronombre impersonal "se" con un verbo reflexivo, ¿debe usar uno "se" o dos "se"? Por ejemplo:

¿Cuál frase es correcta?

Se debe levantarse temprano.
o Se debe levantar temprano.

Cuando se levanta temprano...
o Cuando se se levanta temprano... (i.e. dos "se")

Además, si se usa un verbo reflexivo como un infinitivo con "yo" o "tú", ¿debe reemplazar "se" con "me" o "te"? Por ejemplo:

Debo levantarse temprano.
o Debo levantarme temprano.

Gracias.

Sentences marked as correct or not correct. Added one.

What Rusty said.

The 3 correct sentences that contain "se" are potentially ambiguous: depending on the context, one may understand them as impersonal OR one may understand them as personal (that is, some definite and known third-person singular subject). One could use the subject pronoun "uno" in all of these sentences to imply an impersonal meaning:

Uno se debe levantar temprano.
Uno debe levantarse temprano.

Cuando uno se levanta temprano.

Claro. Gracias a vosotros.

Sometimes the indirect complement "LE" becomes a "SE" when it has the 3rd person form three times in the same sentence, I will make myself clear:

"They killed his son"
"Le mataron al hijo"
"Al hijo se lo mataron"

2nd example: What did you do with the book I gave you?
As you told me, I gave it to her.

¿Qué hiciste con el libro que te di?
Como me dijiste, SE LO di.

(Instead of LE LO, since LE = indirect complement for the 3rd person, LO direct complement, the book itself)