This always fascinated me since they sound almost identical when you first hear them, but when you listen more closely to the notes (especially in the original FDS Metroid), they're definitely different.
But, I happened across these liner notes from the composers here, where Koshiro said it was very directly inspired from the Metroid tune:
Though I think we all know by now that Koshiro is a serial plagiarist.
Still his stuff always sounds like him. Plus the intro to Streets of Rage, man. He's great at conveying a particular mood, even if he heavily samples to do so (not to mention his source material often has a very different atmosphere to it).