I have been tracking UA flite 973 for the past week now and have noticed that this flite leaves Brussels to Chicago twice a day ,once at 11 am and also at about 6pm. Is this a normal practice to use the same flite #twice in the same day, from the same airport? 
That’s an error caused by the flight leaving and re-entering the tracking area. The flight leaves Brussels at around 11 AM CEST and operates only once.
Thanks for your reply and explanation. 
RPinMB