“I was notified that my Google account has been duplicated and now my old address is being changed to this weird temporary address (email@example.com). Should I worry about this? What happened to my normal address (firstname.lastname@example.org)? Will this affect my shared Google Drive docs?”
SHORT ANSWER: Don’t worry. This is normal behavior during the migration to G Suite.
TEMPORARY ALIAS: During the migration process to G Suite, you may still sign in to Google Apps using the temporary username that Google provides (email@example.com). Once the G Suite migration is complete, these conflicting accounts will no longer be an issue.
GOOGLE DRIVE DOCS ACCESS: You should still have access to the Google Drive docs you had in the past. These temp addresses are just an alias Google creates during the migration process and will be back to normal once the migration cutover is complete.