It is commonly believed that Job's original 10 children are in Heaven.
The texts do say that Job received a "twice as much", and that he had "more":
Job 42:10 And the LORD turned the captivity of Job, when he prayed for his friends: also the LORD gave Job twice as much as he had before.
Job 42:12 So the LORD blessed the latter end of Job more than his beginning:
Since all the material items were doubled, it is only natural to wonder why Job had exactly as many "new" children as he had had "old" children.
As far as I know it is near universal to assume Job was blessed in that all of his original children were preserved in Heaven, and that he could look forward to the day when he would be together with all 20 of his children.
Some have wondered why God did not give Job twenty children, fourteen sons and six daughters. I offer two answers: First, the thought of giving birth to twenty children might have been all Job's wife needed again to tempt her spouse to curse God and die! But my simplest and best answer is that God did double Job's family-ten were already alive in heaven. Our family and friends who die in Christ are separated from us for just a little while. They are with Christ and they are enjoying eternal blessings far greater than anything they have known upon this sin-sick world.
http://www.blueletterbible.org/Comm/smith_donald/job/whirlwind10.cfm
After Job prayed for his friends, the Lord restored Job to his former prosperity and gave him double all that he had lost. (Job 42:10) Job had seven more sons and three daughters. This is the same as before and implies that he would see his others in heaven as well! God does everything well!
http://www.bibletrektoday.com/2009/06/03/restoration-of-job/