User blog comment:Rappy 4187/Technical Update: June 18, 2013/@comment-452-20130619020813/@comment-452-20130619235957

I think the problem is mostly that it's attributing it to them now rather than backdating to when they made the contribution. Even a comment saying "Originally added 2010-05-02 02:49 GMT" would help ease that confusion, if actually backdating it isn't technically possible. (I know I can backdate an edit via import, but I don't think I can do that with a file upload)

Good to know that it's visible in the upload log.