After getting some good comments I have updated my guide lines for the Element: Identifier
Label
Identifier
Element Description
This element specifically and uniquely designates the record to provide disambiguation and exact recall.
Required?
Yes
Repeatable?
No
Guidelines for Creation of Content
The unique identifier will be built off of the file name of the image. Copy all of the file name except the file type i.e. “.jpg” into the Element and add “_Alabama_vs_” right before the name of the opposing school.
Examples
75_Alabama_vs_Southern_Mississippi_059
MFB_Alabama_vs_Texas09_KG01616
Let me know what you guys think!
Madam Librarian 
An idea to consider what would happen if you found out that the images had the wrong name associated with them, and some earlier process gave them incorrect information?
Might it be helpful to include a 4 digit year? The two examples have different leading characters, what if you wanted to sort them?
And if the photographer or digitizer has a mistake and you have two images with the same name?
Thanks for the comments. Here are some of my thoughts. While having incorrect information in the Identifier field, let say the name of the opposing team were incorrect, might be confusing it wouldn’t compromise the Identifier’s purpose which is to uniquely designate the record. The patron should look to other fields in the schema for the correct information regarding the opposing team’s name etc.
I considered adding a date element to the Identifier, but after consideration it seems superfluous. The year will be included in the date element, and as we are attempting to make these guidelines as stream lined as possible I decided against it.
Your last question is really good point and a concern as having two images with the same name would negate the unique value of the identifier. By adding the “_Alabama_vs_” the Identifier should not be duplicated with the file name or the same string of information in another database. However, adding the same information to every Identifier wouldn’t remove the chance of duplication as you present it. In fact, I’ll have to think on this one. Another option is to quickly scan through the Identifier field and ensure their are no duplicates.
Can the software automatically scan for identical character strings in this field? If so, it would be easier to enforce uniqueness across the digital library.
Now that we have begun to think more locally for this collection, I think using the filename is a fine idea. Since all images are from the same collection, the likelihood of the filenames not being unique is low due to the chances that duplication would have been caught at the time the image was scanned and saved (i.e. the filename would have shown up with “(1)” or similar appended).
Also, this method let me do my unique identifiers in a matter of minutes. Applause for efficiency! 🙂