Fields missing from "Drupal Fields" list

I tried 6.x-0.4 on my test site. The good news is that File Upload worked fine. But when matching CSV fields to Drupal Fields, not all my Drupal Fields were displayed; two were missing. However, a bogus field named "left" was displayed instead. See attached screen capture. FWIW, the two fields which were not displayed were created using the Profile module, are of type textfield, and are named "First Name" and "Last Name".