This document describes a new method for tracking cells that collide in microscope videos. It presents 3 key challenges: 1) cells' motion and appearance can change abruptly during collisions, 2) previous methods used single hypotheses that cannot handle collisions well, 3) manual tracking is tedious and expensive. The proposed method addresses these by using multiple hypotheses about collision states, Kalman filtering for reliability, and detecting/tracking cells in videos in a step-by-step process. Experiments show it achieves an 88% coverage of colliding cell positions, outperforming other methods.