What caused the formation of the tornado to multiple?

The appears to be asking about multiple vortex tornadoes. The process of how a tornado becomes multiple vortex is called vortex breakdown. Thi occurs when the wind in a tornado is spinning so fast that it cannot reach the center. The low pressure instead draws air down the middle. This causes the tornado to expand. When the downward moving air reaches the ground it spreads out. Complex interactions between this outward moving air and air flowing into the tornado leads to the formation of smaller vortices within the tornado.