correct, but as i said, some peeps are not able to identify correctly which bearing may be breaking down, as the OP has asked, i would assume that he is unsure how or what to check for. no disrespect.
If you are that way inclined, IE, hands on with 30 years experience in mechanical engineering, it's a simple diagnosis and cheap fix, however if you aren't that way inclined, where would you start, you would ask a question as the OP has done and wait for replies or more experienced people, thats how we learn.
It was quite strange, as when this question was posted, I was actually watching a motor program with Ed China, who was changing a wheel bearing on a dodge Charger, even he suggested that both should be changed together.
If you had a pair of bearings that had done say for arguments sake, 60k miles, and one had started to fail, would you question yourself if you should change both?
It's such a simple quick job. IMO, if your doing one, just do both. Stress loading on the bearings would have been quite large and if one is failing, this would naturally put added stress on the other bearing.
With out a bearing vibration pen, you can only feel and listen for a bearing breaking down, this comes with experience.
We each have our opinions, and this is mine, no offence meant to anyone, and I am always open to differing ways of doing things.
I would change both, no question, no recourse to do the other at a later date.
We may have to agree too disagree on this
Thanks Vik....