I am wondering about something concerning prophecy. I have been hearing that a prophecy can have more than one fulfillment. That seems a bit like an oxymoron to me because to fulfill it means that it is complete, or done. So how can it be completed or done twice?

The issue right now is the passage in Matt and Mark and the mount of Transfiguration. One has told me that the Lord Himself gave a dual fulfillment right there of the prophet Elijah. What i mean is, that Jesus said that Elijah is going to come first, and that he already has come, meaning John the baptist. Here are the passages.

Quote
Matthew 17:9
Now as they came down from the mountain, Jesus commanded them, saying, "Tell the vision to no one until the Son of Man is risen from the dead."
17:10
And His disciples asked Him, saying, "Why then do the scribes say that Elijah must come first?"
17:11
Jesus answered and said to them, "Indeed, Elijah is coming first and will restore all things.
17:12
But I say to you that Elijah has come already, and they did not know him but did to him whatever they wished. Likewise the Son of Man is also about to suffer at their hands."
17:13
Then the disciples understood that He spoke to them of John the Baptist.
and

Quote
Mark 9
9:9
Now as they came down from the mountain, He commanded them that they should tell no one the things they had seen, till the Son of Man had risen from the dead.
9:10
So they kept this word to themselves, questioning what the rising from the dead meant.
9:11
And they asked Him, saying, "Why do the scribes say that Elijah must come first?"
9:12
Then He answered and told them, "Indeed, Elijah is coming first and restores all things. And how is it written concerning the Son of Man, that He must suffer many things and be treated with contempt?
9:13
But I say to you that Elijah has also come, and they did to him whatever they wished, as it is written of him."
This is about Jesus and what He said concerning Elijah. They are saying that John the Baptist was Elijah, and that another Elijah is yet to come. That Jesus says so here in these passages.

I hope that made sense lol. If it doesn't, I will try hard to make it more clear. But is there such a thing as dual fulfillment of prophecy? Is this in fact a prophecy fulfilled in John the Baptist that has yet to be fulfilled again at some future date? Any thoughts on this are much appreciated.

Michele