Why is my Facebook account logged onto multiple devices?

I was just randomly checking my account settings and was looking at devices that are logged onto my Facebook and it shows multiple devices, all from iphone 7plus which is what I have. This might be a stupid question, but wouldn't it just say iphone 7plus once if my phone is the only one logged onto Facebook? On my account settings, it shows 5 other iPhone 7 plus. Does this mean someone else is using my Facebook? I'm just really confused.

Somebody else could have hacked your Facebook

It could be hacking related or it could simply just be a Facebook malfunction. At the very least for peace of mind, I'd advocate getting a VPN app on your one and only iPhone 7 Plus. Facebook is obviously the #1 social profiling type of website, meaning the likelihood of someone wanting to target just you in particular is theoretically pretty low in probability.

I'd be more concerned about having your profile look more like you're on the go a lot to prospective employers/acquaintances (and also without divulging information you'd regret). But with all this said, if any of your friends actually also own an iPhone 7 Plus as well, I guess it would pay off to not necessarily be nosy/invasive but to nonetheless pay a certain amount of attention to what their predominant phone activities seem to revolve around.

Sometimes it will say that if you Drive to a Different Town or City sometimes it will Pick up that Location

But just to be on the Safe Side it may not be a Bad Idea to change your Password