Copying your photos to Google Photos in the cloud is good. Saving those photos to another cloud service is a true backup.
Mrs. Geek recommends Microsoft One Drive as the secondary storage. You get 1TB of storage for your files with an Office 365 Subscription.
Thank you for the info on backing up Google Photos! I’ve been wondering (well, worrying a little…) about how safe my 39,0000 pictures (you have me beat!) are and if I should be backing them up. It’s such a hassle to do it on an external hard drive! Then I watched your video about backing up to Onedrive, so I installed it on my PC and my phone, BUT it only uploaded the most recent (it says my Camera Roll, whatever that is!). How do I back up all my pictures that are in Google Photos in Onedrive? Thank you!!!!