I would say it depends on how long it's been happening and whether you're getting any other errors. I believe what happens when you get the 'already logged in' error is that your character I'm the game is still loaded even though the game is closed, so it sometimes takes a while for you to actually 'log out'. It tends to clear itself up relatively quickly though, from my experience, within 5 or so minutes. There are times when it's being super stubborn and might take 10 or longer, but those are rare instances.
I would say I doubt it's hacking since even if someone did know your login info they likely couldn't log in on another computer while the account is already logged in (because it's already in use), but I don't actually know if being logged in prevents you from logging in on another computer, or if it would boot you on the first computer and log you in on the second.
Character List [RP and PvE]:
Stands-Against-Death: Argonian Magplar Healer - Crafter
Krisiel: Redguard Stamsorc DPS - Literally crazy Werewolf, no like legit insane. She nuts
Kiju Veran: Khajiit Stamblade DPS - Ex-Fighters Guild Suthay who likes to punch things, nicknamed Tinykat
Niralae Elsinal: Altmer Stamsorc DPS - Young Altmer with way too much Magicka
Sarah Lacroix: Breton Magsorc DPS - Fledgling Vampire who drinks too much water
Slondor: Nord Tankblade - TESified verson of Slenderman
Marius Vastino: Imperial <insert role here> - Sarah's apathetic sire who likes to monologue
Delthor Rellenar: Dunmer Magknight DPS - Sarah's ex who's a certified psychopath
Lirawyn Calatare: Altmer Magplar Healer - Traveling performer and bard who's 101% vanilla bean
Gondryn Beldeau: Breton Tankplar - Sarah's Mages Guild mentor and certified badass old person
Gwendolyn Jenelle: Breton Magplar Healer - Friendly healer with a coffee addiction
Soliril Larethian- Altmer Magblade DPS - Blind alchemist who uses animals to see and brews plagues in his spare time
Tevril Rallenar: Dunmer Stamcro DPS - Delthor's "special" younger brother who raises small animals as friends
Celeroth Calatare: Bosmer <insert role here> - Shapeshifting Bosmer with enough sass to fill Valenwood
PC - NA - EP - CP1000+
Avid RPer. Hit me up in-game @Ras_Lei if you're interested in getting together for some arr-pee shenanigans!
This was actually mentioned in the patch notes, idk if it was Harrowstorm or Dragonhold or maybe a tiny bit earlier. It’s intentional to get the message in order to prevent you from accessing the server too quickly. A lot of times this is frustrating because it extends the time until you can get back into the game when you crash in a raid.
As the server gets more unstable, they put in more bandaid fixes.