60 LED chaser sequencer, two LEDs turn on at a time instead of one
The 4017 is a decoded decade counter which means that one of its outputs is always on. So at reset Q0 is active this will apply to both IC3 and IC4. When you clock IC3 it changes the active output from Q0 to Q1.

If you are trying to achieve a single light that runs from one end of a display to the other you would probably be better off building a shift register to do that using something like several 74HC595s.