Reception has nothing to do with the number of stopbits.

It's the transmitter where you have to set it. The extra stopbit is meant to provide to the receiving device (microcontroller, computer, but mostly teletype) to "execute" the received character; hence for the receiver the extra stopbit presents only a one bit's time delay before the subsequent character's startbit (it is only historical and has no real meaning today, as all modern UART's receivers have double buffer, (and there are no teletypes anymore :-) ) ). The receiver shall not check for its presence.

JW

PS. Ask us for TRANSMITTING 2 stopbits AND parity - on '51 - well, that's much more of an interesting task (but then not so much at 300 Bauds...)