Most digital cameras reset their file numbering system to zero somewhere around 10,000 images. That creates the possibility of duplicate file numbers, posing the potential to accidentally overwrite an existing file. I simply renumber my images with a Custom Preset when Importing to Lightroom. In Lightroom > File > Import Photos from Disk > select your card to open it in the Import Photos dialog box.
Template 1. Select Edit from the pull down menu. 2. Select and delete anything existing in the editing window. 3. Choose the Date pull down menu > select YYYYMMDD > then click Insert. Notice it's appearance in the edit window above. 4. Click the cursor in the edit window "exactly" behind YYYYMMDD and add an underscore _ i.e. yyyymmdd_ no spaces!
Custom Text Option You may want to name the file with custom text: job name, location etc. 1. Choose Custom Text > then click Insert followed by the underscore, i.e. customtext_ no spaces! You don't have to fill in the custom text at this point, just fill it in on Import. If no custom text is entered, a dialog box alert will appear. Simply acknowledge to dismiss.
Sequence Select a three digit or greater numbering sequence from the pull down > then click Insert.
Preset [at the top] Select Save Current Settings as New Preset from the pull down menu. Name the Preset something you can recognize [something like yyyymmdd_customtext_0001.ext] > then click Done.
Import Choose the custom Preset you just created from Template: > then Import. The files will be automagically renumbered to something like 20090623_smithwedding_0349.ext where 2009 = year 06 = month 23= day smithwedding = custom text .0349 = image #349 of the shoot, and .ext = the file type you assign NEF, CRW, DNG, JPEG etc. In the Library Panel > Metadata, the Original File Name [as it came from camera] is always available.
Notes 1. You can also renumber existing files on your drive in Library > Rename Photos > choose the Custom Preset > then navigate to the folders in question. 2. Remove any spaces in file names, it will save lots of headaches when moving files to other operating systems and servers. Use either birdphoto, bird_photo or bird-photo.