No, the first letter was from Boris and the second letter was also from Boris. The first letter has not been notarized. Therefore, Boris is complying with the law made by elected dictators by sending the letter but has not made the letter legally binding. The second letter has been signed requesting that no extension be made and has been notarized meaning that we are leaving the on the 31st of October.
What EU law on the matter is, is unclear. But I understand that there are directives to stop coercion and the Staylinist, democracy hating ,elected dictators in parliament did coerce Boris into sending the unsigned letter.