To my knowledge, the longest pikes ever used in war are the Late Hellenistic phalangites' sarissa pikes, which could be over 20 feet in length. However, these were still meant to be wielded by one person. When pikemen made a comeback in the 15th century AD, the pikes they used were significantly shorter.

The problem with a 2-man pike would be that it severely reduces the mobility and flexibility of the men carrying it. This is already a problem with the sarissa; anyone who could get beyond the pike's point could no longer be harmed by the pikeman, and anyone who could get at a block of pikemen from the side or rear would render the pikemen completely helpless. For protection, men wielding long pikes must rely on wide, dense formations, which in turn are vulnerable to disruption when moving across a battlefield. A field wall, a ditch, a slope, even a single tree can cause major disruption in a pike formation. Unless the battlefield was prepared in advance, pikemen could be easily thrown into chaos. All of these problems would be massively worsened by the use of pikes that need 2 men to wield them.

Meanwhile it's hard to see what advantage could be gained from yoking 2 men to a single pike. They wouldn't be able to do anything more than a single man could do, and if each man has one pike, those 2 men also have two deadly weapons aimed at the enemy instead of one.