What you are seeing is the effect of having two fields named Account Name. The count for - will equal the sum of all other Account Names.
Use this to check the first entry for a value, and if its null then get the second entries value:
eval User = if(isnull(Account_Name), User_Name, mvindex(Account_Name,1))
This will create the new value User, but you will probably have to 'View all fields' to see it.
The User field will not contain -.
You can find more information here:
http://answers.splunk.com/answers/2649/same-fields-with-different-values-in-one-event
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