Have you considered changing your file naming pattern? I use an 11 digit file name for my images, but you could shorten it a couple digits if you only shoot with one camera and don't need that info. Using todays date, it would be 200815 (20 is the year, 08 is the month, 15 is the day of the month), that way each file has a unique name. If you are doing less than 999 files at a time, all you would need is to start the first file as 001, sequentially through your 200 some odd files. I use your OS systems "Automator" application to add the date and that can be done a folder at a time, if the exact date of when the file was taken isn't important you could do the folder you have currently gathered your files into, 999 files at a time by changing the the "day" part of the sequence by going back a few day into the past.
You could still leave the "photo" part of the name that you currently have by adding a "-" at the end of your digits, giving you "200815-photo001.jpg" or have "Automator" remove "photo" and have "200815001" through your 200 some odd file. "Automator" works in the finder to do the naming changes. Initially it will be a bit of work but it is better than loosing images files the way you are currently doing it...
I usually put the folder I am using this naming sequence to an upper level in the Finder, such as the Desktop Folder or Downloads Folder so you don't have to dig very deep into each folder to find them.
BE Well,
Greg