Why are there 2 wires taped together? 2 white and 2 black
That's known as a pigtail. A black and white wire come in to feed the box, a black and white wire leave the box to feed something else. They are connected together with that short piece to feed the outlet. It's easier than messing with 4 wires in and out of the outlet and replacing outlets is easier.
Those connections should be redone with wire nuts and the connections to the outlets should be on the screws, not the backstabs. Shepherd hook the Black wire to brass screw, white wire to silver screw. If those wires are aluminum you'll need special outlets and block connectors.