I easily get around it by modifying the code to check the filename to ensure we don't do the same file twice in a row:
def runAction(self, event):
# Grab the file name and data
filename = event.file.name
filedata = event.file.getString()
# Check if this file has just been uploaded - to stop a double import (potential platform/browser bug)
if filename <> self.custom.filename:
# Call the import function on the table
self.parent.parent.getChild("Table").importCSV(filename, filedata)
self.custom.filename = filename
else:
self.custom.filename = ''