Symbolism, Imagery, Allegory
Is Elisha just the B-Side Elijah? Even though he does many of the same things Elijah did, the answer needs to be "No." Elisha performs unique miracles of his own—think about the kid-killing bears, which we've covered elsewhere.
Many of these miracles, for Christians (or in a general literary way), foreshadow the miracles of Christ. When Elisha manages to feed a crowd of people with a limited number of loaves of bread, this foreshadows Jesus doing the same thing in Matthew 14:13-21. The same goes for healing Naaman from leprosy (Jesus heals multiple lepers).
One of the most interesting of Elisha's miracles is when he resurrects a child from the dead (which, again, is rather similar to Jesus resurrecting Lazarus from the dead). Although the procedure isn't really described, Elisha uses some sort of magical, prophetic technique to accomplish this task—laying on top of the boy and apparently transferring some of his own spirit into him. The boy sneezes seven times and comes back to life (seven being a symbolic number of good fortune).
Ultimately, Elisha doesn't exactly take credit for his miracles—they're made possible through the power of God. They symbolize the prophets' unique relationship with God. By being humble and devoted, by believing that he or she personally doesn't have any real power in the grand scheme of things, they end up gaining far more power than a merely proud person would be capable of gaining. (Isaiah is actually far more powerful than Sennacherib, for example.) Their ability to hold and keep that power is related to their humility.