An excellent example of duality is found in a prediction Joel made about the Holy Spirit (Joel 2:28-32 Joel 2:28-32  And it shall come to pass afterward, that I will pour out my spirit on all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions:
 And also on the servants and on the handmaids in those days will I pour out my spirit.
 And I will show wonders in the heavens and in the earth, blood, and fire, and pillars of smoke.
 The sun shall be turned into darkness, and the moon into blood, before the great and terrible day of the LORD come.
 And it shall come to pass, that whoever shall call on the name of the LORD shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the LORD has said, and in the remnant whom the LORD shall call.
American King James Version×- Joel 3:1-2 Joel 3:1-2  For, behold, in those days, and in that time, when I shall bring again the captivity of Judah and Jerusalem,  I will also gather all nations, and will bring them down into the valley of Jehoshaphat, and will plead with them there for my people and for my heritage Israel, whom they have scattered among the nations, and parted my land.
American King James Version×).
God inspired the apostle Peter to quote from this passage to describe events on the Day of Pentecost, when God founded the Church after Jesus' resurrection (Acts 2:14-21 Acts 2:14-21  But Peter, standing up with the eleven, lifted up his voice, and said to them, You men of Judaea, and all you that dwell at Jerusalem, be this known to you, and listen to my words:
 For these are not drunken, as you suppose, seeing it is but the third hour of the day.
 But this is that which was spoken by the prophet Joel;
 And it shall come to pass in the last days, said God, I will pour out of my Spirit on all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams:
 And on my servants and on my handmaidens I will pour out in those days of my Spirit; and they shall prophesy:
 And I will show wonders in heaven above, and signs in the earth beneath; blood, and fire, and vapor of smoke:
 The sun shall be turned into darkness, and the moon into blood, before the great and notable day of the Lord come:
 And it shall come to pass, that whoever shall call on the name of the Lord shall be saved.
American King James Version×). Miraculous manifestations of God's power through the Holy Spirit did indeed occur then (Acts 2:1-12 Acts 2:1-12  And when the day of Pentecost was fully come, they were all with one accord in one place.  And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting.  And there appeared to them cloven tongues like as of fire, and it sat on each of them.  And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance.  And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven.  Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language.  And they were all amazed and marveled, saying one to another, Behold, are not all these which speak Galilaeans?  And how hear we every man in our own tongue, wherein we were born?  Parthians, and Medes, and Elamites, and the dwellers in Mesopotamia, and in Judaea, and Cappadocia, in Pontus, and Asia,  Phrygia, and Pamphylia, in Egypt, and in the parts of Libya about Cyrene, and strangers of Rome, Jews and proselytes,  Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God.  And they were all amazed, and were in doubt, saying one to another, What means this?
American King James Version×). But these were only the first fulfillment of Joel's prophecy. The ultimate fulfillment will come at the time of the end and will involve, among other things, the gathering of the nations to God's judgment in the Valley of Jehoshaphat. This did not occur on the Day of Pentecost. So we see that prophecies can be dual.
In a similar fashion, God inspired many other prophecies with dual meanings. They applied as warnings to the Israelites at that time and as warnings to the modern descendants of those same people. The people of Britain, the United States, Canada, Australia and New Zealand and the nations of northwest Europe who represent these people today would do well to heed these warnings.