Realms still happens in singleplayer

I logged out of realms, and went to play in singleplayer. However, I was stuck in the place where I had logged out in realms, despite being in my singleplayer world. In addition, I still had an armor bar, despite having no armor in singleplayer, and having everything else in my singleplayer consistent with my singleplayer world. I quit to title, and went back in, but the glitch still happened. I got chat from the realm, and the sky would swap with the realms sky around once every second. People in the realm could see what I sent, too. I checked on my alt account, which was also open, and it said my main was still in the realm, despite it being in singleplayer in the other window I closed both windows, and I turned on Minecraft again, and it was normal. My friend, who does not have an alt, said he experienced this glitch too.