You could try this

SELECT DISTINCT file_format FROM table
[download]

That would tell you all the methods of variable interpolation that have been used. Then use

UPDATE table SET file_format='p$b.zip' WHERE file_format IN (....)
[download]

to put them into a consistent format. Then update your procedures so it doesn't happen again. Or maybe you want to do that first?

Have fun,
Carl Forde