User blog comment:ImperiexSeed/Supernatural Mysteries/@comment-1509826-20120408181109/@comment-3481504-20120408181723

That's a good question. I think that was discrepant, as it seemed as the Gabriel that talked to Dean, was really him. So maybe he did it while talking with Lucifer, however he'd likely have noticed.

Regardless, Gabriel's powerful, and actually probably could make strong copy of himself.