So I have 4/5 license files all different sizes, I need to find out how big each license file is, is there a way of telling from within the files ? each one looks completely different and its not clear which file is for which size license.
Do you have access to your support portal?
If you go under 'My Licences' then sort by 'Current' you should see your licence size and GUID.
Mapping the GUID should allow you to sort them out.
probably an administrative oversight?
licences may have been attributed to other people in your org?
Either way, follow up with your Sales rep as having those licences in your support portal can be helpful in case you need to recover them, or verify which is one is which.