You can do this by opening all the input reports at once (Monarch can handle up to 1024).
If you then create a calculated field Filename of the type Character, with the expression:
this should return the filename. (File() on its own would return the whole path, e.g. "C:\documents\terry\C_EE_153.txt" instead of "C_EE_153.txt".)
Now using the split on key values option for summary exports in Monarch v10, it should be easy to use Filename as a key value, and to split the exports on that automatically.
First off, don't be sorry: we were all new to this at one stage.
Secondly, this is an unusual and not at all intuitive challenge, for which Olly has present a very usable and easy to implement solution.
Additionally, if you wanted to calculate something like variance analysis for company A and company B values (assuming that is something you'd need to do), you could use the file name as an Across key field, and use the report number (extracted from within the file name) as the first Down key field.
To extract the report number from within the filename, create a calculated Character field with this formula: