In prophecy there is the concept of a near and a far fulfillment, or a dual fulfillment. That is, the prophecy applies to the current situation of the prophet who is speaking, but also points to a more distant future fulfillment.
Consider 1 Chronicles 17:11-14, where God made a promise to David to establish his throne in his seed forever. David quoted this in 1 Chronicles 22:9-10 specifically about Solomon. However, this hasn’t been completely fulfilled yet, as currently no one is sitting on the throne of David.
The angel Gabriel who came to tell Mary that she would have a child in Luke 1:33 uses this same language applied to the Lord Jesus, who “will reign over the house of Jacob forever, and of His kingdom there will be no end.” [1]
This is an example where there was a fulfillment in the days of the original prophet, but there is another, richer, fulfillment at a later date as well.
In many Messianic prophecies a variation of this concept applies. In many cases part of the prophecy applies to the first advent of the Lord Jesus, while the rest of the prophecy applies to the second, future advent. This is more a split fulfillment rather than a dual fulfillment.
For example:
Psalm 22 is split into two, verses 1-21 dealing with the suffering of the Messiah on the cross and verses 22-31 dealing with the coming Kingdom.
Zechariah 9:9 considers the triumphant entry, and 9:10 concerns the establishment and extent of the Kingdom.
Zechariah 13:7 speaks of the cross, and 13:8-9 look forward to the tribulation, the Day of the Lord.
In each of these cases and many others the passage refers to two distinct timeframes, including many cases where the same sentence is split into two different times. Generally, it seems that to the prophets it wasn’t even revealed that there were two timeframes in the prophecy. Only when one part was fulfilled did it become clear that there was a division of time contained in the prophecy.
This is crucial for a discussion regarding whether future prophecy, those prophecies that have not yet been fulfilled, should be interpreted literally or allegorically.