There is a decent article on Brittanica about the historical use of spears as a weapon, although it only focuses on European development.
As a great man once said, "Shields are for hiding behind." Only slightly less famous is the commentary of edged weapons, "The pointy end goes into the other man."
The point (pun intended) is, spears are designed for mass use to stick the other guys before they can stick you. The Roman pilum was designed to bend on impact, preventing the enemy from tossing it back (with the nice bonus it snared any shields it stuck into).
Any modification of the haft of the spear to make it a more convenient single-handed weapon also reduce its effectiveness. It's just not a good design for single combat at melee range, unless you treat it as a pointy quarterstaff - in which case there's no way to effectively wield two of them, unless you have four hands and an ungodly amount of dexterity.
Many swords, by contrast with spears, are designed for one-handed operation (greatswords excepted). Even with rapiers, which are designed for the gentleman duellist, the Florentine style or brace of rapiers (dual wielding two full-size swords, as illustrated by Agrippa) requires significant training to be more than a death trap for the wielder.
Even in feudal Japan, it took until the 1600s for the advent of Miyamoto Musashi's quite radical Niten Ichi-ryū school of swordsmanship that introduced the idea of dual wielding katanas effectively.
Let's imagine for a moment you have two spears of moderate length, and you are an expert at using them together. You have all the pitfalls of Florentine, with none of the inbuilt safety mechanisms. If you parry with a single spear, there is no guard to stop a blade from sliding up and chopping off your fingers. If you catch your opponent's blade with both of them, you have no way to bind the blade with a single spear to return the second one to play. If your thrust is parried, there is no edge on the inside with which to cut. If you happen to fight someone with a shield, the best you can hope for is to stab their foot and so hope to manipulate an outcome that way. The spear by itself is not equipped for complex defense.
Video games and movies are wont to make us believe the fantastic (which I am all in favor of), but there is scant evidence dual wielding spears would be a winning combination. It is precisely these limitations that caused other permutations and the abandonment of the spear in its purest form for general use.