Yes, It is possible for a female to be impregnated by multiple males. Cats are induced ovulators which means that they ovulate whenever they are with a male. It is definitely possible for your cats to be from different fathers, however, it is also possible that your cats are just expressing different genes from the same parents.
My 3 year old cat will occaisionally switch moods, rather quickly, from playful to attack mode. She will bite me and gets a strange look in her eye. The only way to break this is to put her in a room by herself. It is almost like she is “hunting” me.
Cats hunt their prey and indoor cats often mimick this behavior with their human housemates. By closing her in a room, you are stopping the game. If you don’t want her to do this, puting her in another room is a good option. Using a can with pennies in it and shaking it when she tries to attack you will also have the same affect.