Sometimes a photo can find itself in multiple places at once on your computer! That's why, if you upload photos to your gallery that happen to have the same file name, PhotoDay will automatically alert you via the upload window in the bottom left-hand corner of your dashboard.
This window will give you the option to either replace a duplicate file with the newer version, or to skip the upload of the new photo entirely. There are two more options at the bottom of this window as well, in case you wish to batch replace or skip all duplicates during your upload.