Hey there again, moondawg009!
I don't think it's an overkill, it really depends on your intended purpose for the newly acquired storage devices and the amount of data you'd be saving onto it. Indeed, most people use the SSD for their OS and most demanding applications like games, editing software, etc. Whereas, the HDD serves as a secondary storage for all massive files like movies, raw software files, gameplay recordings, media files, etc.
Either way, you should always keep off-site backups on external drives or some other storage device. Having at least two copies of your data stored in different locations is the surest way to avoid the headaches of potential data loss.
Hope I was helpful. Best of luck!
SuperSoph_WD