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Thanks for pointing that out; it was an omission on my part.
However, I don't think that Lightroom's handling of time and date changes is robust enough. I would personally use a tool like EXIFTool or Attribute Magic Pro over Lightroom to make changes.
The principal reason is that Lightroom changes to date and time for raw files are saved in its internal database unless you specifically instruct it to write the changes to the file, so time and date changes are not automatically reflected in the search function of your operating system. And you'll probably also have to allow write access to the files if they were originally read-only.
Also, an operating system can display at least 10 time fields associated with an image file; fields like Date, Date Created, Date Modified, Date Taken, Date Acquired, Date Last Saved, etc. Lightroom is incapable of changing all the time and date fields and this can cause screwy results if you're using Finder or Windows Explorer to do complex date searches.
For example, if you use the option to "Change to file creation date for each image," Lightroom will change fields like Date Created and Date Last Saved, but it will not change the two important fields generated by the camera - Date, and Date/Time Digitized.
Similarly if you use the "Adjust to a specific date and time" option, Lightroom will not change the Date Taken field.
So in my opinion there are much better file attributes editors that can make these adjustments to your files, then import the files into Lightroom.
Verify that the clocks in both cameras are set to the same time; a common error is that one camera is 12 hours ahead of the other. Then from the menu click on View > Sort > Capture Time (also make sure Ascending is selected).
If they are off by hours (not mins/secs) you can also adjust the capture times in LR (Library > Metadata > Edit Capture Time...) first select the ones you want to change by filtering on Metadata and choosing the camera that has the date wrong.
I use PhotoMechanic to do this because it allows relative time adjustment in yrs/months/days/hrs/mins/seconds.