To backup photos to multiple Flickr accounts go to accounts tab, click on the plus sign you see in front of ‘Flickr’. By clicking this you can add a number of Flickr accounts. However, only one of those will have ‘active’ status and for others you’ll see ‘activate’ status. Select the account you want to use when you are ready to backup and follow the usual upload process. Once done, you can switch between accounts for different backups very easily.
PicBackMan is a free photo/video uploader that helps you to keep your memories backed up to your favorite online services.
Users in 130+ countries have backed up.
... an excellent job of uploading more then 300GB of photos to 2 different services