Random people automatically appearing on my Facebook friends list

I keep a very tight control of who I accept on Facebook, I only have names on Facebook who I know and careful who I accept.
Once in a while I go through my friends list, find a few names I don't recognise, it has been suspicious that something is going on, change my password and move on.

This time I found 20 names. When I check on their names it says that their account is deactivated (ALL OF THEM DEACTIVATED).

I KNOW that I did not send or accept friend requests from these people.
I ONLY use Facebook on my own devices (Android with lookout security, iPad with 5.1.1, Laptop running Windows 8 (Built in Security Essentials).
I use a UNIQUE email address ONLY for Facebook logins and notfiications which has been changed since last time I checked through my friends list.
I NEVER use Facebook to authenticate to websites
The ONLY Apps which have approval are Spotify & Instagram.
All other games, apps, etc. have has their permissions revoked since last time I checked through my friends list. I keep a very tight leash on my Facebook "privacy" now.

There was a time, a long long time ago (about 3 years ago), I DID send lots of Friend requests because at low point my my life where I was in a ****ty job and playing Mafia Wars a lot for lack of better things to be doing, including one time I sent friend requests in bulk by email address. Since about 2 years ago, I deleted EVERYONE who I added via. Mafia Wars, and also went into the friend request pending by email section (I don't think they have this page anymore) and DELETED everyone with friend requests outstanding who didn't accept me at the time.

I don't know if this is still a having a ripple effect from the Mafia Wars invites I sent out long ago and maybe only being accepted now. I do have email notifications turned on for when someone wants to Add me as a friend, and for when someone accepts my friend request, and I am not getting such emails to confirm this to be the case.

Maybe this is some other security issue (Hijack control of Facebook from a malicious webpage?) Maybe there is an ongoing security issue? Maybe this is a Facebook bug?

Has anyone heard or seen this before?

Attached some screenshots of examples.

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