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.