Assume we look an a certain port say, port number 1234.

Are there TWO different ports 1234 - one for the outgoing direction and one for the incoming?
Or is there only one port which can be used only in one direction at a certain time: either
as incoming or outgoing?

If the ladder would be true then an already established incoming connection on port 1234 would block
any outgoing connection on the same port.

Peter