You can have a form rule to enforce the population of the concatenated State and Event Name.
Make a formula field
List("-", [State], [Event Name])
And have a form rule force that value from the formula field into a scalar data entry field.
Then you will have a unique identifier and you should be able to import and merge on that field. I don't think you will have to change that to be the key field of the table but you could certainly change the key field of the table to be that unique identifier and that would probably be best.
------------------------------
Mark Shnier (YQC)
mark.shnier@gmail.com
------------------------------