Mazda Repair: Wheel bearing repair, front wheel bearing, wheel bearing repair

Question
Wanted to ask you opinion about the episode that's unfolding with my wife's mazda 3.  She heard some clicking and took the car in for a check and repairs and yesterday the mechanic called and wanted approval for the wheel bearing on the front right to be replaced.  Went ahead and gave him the okay.  Now, after finishing that, he stated that the car still had a problem and found the left front wheel bearing should be replaced as well.  Was wondering what is the likelihood that both wheel bearings were damaged and needed to be replaced or should I be questioning their diagnostic acumen.  My wife does state that there was an incident where she drove onto a curb and the car had been at the same dealership just a little less than a year ago with a clean bill of health.  That's all the related history I can give other than to say my wife is not riding it in an excessively rough fashion like a teenager might.  Any thoughts?

Answer
bearings tend to wear in the same manure but hiting something on one side might cause it to wear differently and permaturely but normally when one is in motion the other is also in motion like brakes when one is applied all are applied so they typically wear at the same time. you should get around 100-150km on wheel bearing hubs in normally driving it is possible that they both needed to be done.  a wine is normally heard at certain speeds when they go. ask for the old ones and turn them by hand and listen closely for any unnormal grinding or binding sound