I watched the Libby parts too and I am sure the on the frieghter was different from in the hospital..

Couple reasons:
On the freighter, we hear the song that was playing when Michael drove his car into whatever that was.. Then I had my stereo turned up loud and hear what I thought were faint whispers almost.. Then she appears..

In the hospital: We see Libby carring in Blankets just like when he shot her, so I think it was more a bad nightmare.

__________________
Please don't give up, Des. Because all we really need to survive is one person who truly loves us. And you have her. I will wait for
you. Always. I love you, Pen

DESMOND: I love you, Penny. I've always loved you. I'm so sorry. I love you!
PENNY: I love you too.
DESMOND: I don't know where I am, but--
PENNY: I'll find you, Des--
DESMOND: --I promise--
PENNY: --no matter what--
DESMOND: --I'll come back to you--
PENNY: --I won't give up--
BOTH: I promise. I love you.