Ender Dragon multiplying bug

Hello,

i started playing Minecraft on this particular device (Toshiba laptop) around 1 month ago. I was playing normal survival perfectly fine, then i went to the end to kill the Ender dragon i died by being thrown off the main end island. i then went straight back to the stronghold then the end again. I was caught off guard as there was not just one Ender dragon, But Two! now every time i die there is another one repswaning. i have attached a photo of this particular bug. thanks