Hi Liam,
Basically when you upload a file into Collect, the original file name is lost and Collect assigns a unique name to it. Of course if you upload data from multiple devices into a single instance of Collect, the name that has been assigned could be no more unique because will be relative to another system, so Collect, during data import, will assign again a new name to the file.
Nowadays there is no way to access the uploaded pictures without opening the record from the data management. We are planning to add a sort of "uploaded files manager" but it will be available only next year...
Meanwhile you can access the uploaded files opening the .collect-data file generated by the data export: the files are stored inside a folder "upload", divided into subfolders by survey and attribute (survey internal id and attribute internal ID are used as folder names).
Thanks,
Open Foris Team