I wonder, what will he do after quitting the reporting thing completely.

Have a major mental breakdown? You'd never guess how much I love him based on the sort of things I put him through in my imagination.

And the Captain must be very pleased that now he is dreaming of two Tintins instead of one. Or will the 'real' Tintin merge into the 'dream' Tintin?

There's only one Tintin - he walks into the Captain's nightmare of being left alone forever. Captain Haddock thinks Tintin is a ghost and Tintin is trying to persuade him that it's just a dream, but also real. Captain Haddock is all like "This isn't a dream because in my dreams, you're always naked." And Tintin is throughly shocked, but willing to do whatever he has to do to make the Captain listen to what he has to say.