Why do some conferences with double blind review ask for author names when submitting the paper for review? I wonder why some conferences with double blind review ask for author names when submitting the paper for review. Why not asking for author information once the paper has been accepted?
Likely so they can track the papers internally by author. It prevents, for example, a submission being sent out to a reviewer who is on the paper.'

Double-blind just means that the reviewers are unknown to the author, and the author is unknown to the reviewers. It doesn't say anything about the conference organizers/editorial staff.