Both vfat.img's are the exact same, and ARE NOT symlinks. However, deleting one will delete the other. Here's why:

ubi:storage is mounted in two places, /fridge and /intstorage. Both mountpoints use the same block device(storage device), ubi:storage.

Due to the nature of how enTourage partitioned the NAND on the Pocket eDGe(may also apply to the full-size version as well), the internal storage cannot easily be used for normal storage without some extra work. Namely, copying everything from /data into /intstorage, then making the system at boot mount ubi:storage on /data instead of ubi:userdata mounting on /data.

By default, /data and /system NAND partitions are both 329288KB in size. /system is basically the firmware which is upgraded when the device is updated, along with a few ramdisk images. /data is not changed during an update, as it stores user settings and downloaded apps. This applies to Android on phones as well.

If you really want to utilize the ubi:storage as /data, you can download the latest update.zip and edit some of the start-up scripts to change the mountpoints. This has not been tested and I am not totally sure what the end effect will be, it may work, or it may cause problems, if the system expects it a specific way. If you try this, be sure to have an official update.zip handy to flash back the original manufacturer image. On the page you can download the update.zip, it will tell you how to manually update using a update.zip file.

Hope this information helps.