Hi
First of all good luck in Paris on Sunday.Secondly a 2nd Marathon in 6 weeks is possible.I ran in Berlin in 2002/3 and a week later on both occasions London to Brighton ( 88km ) without too many problems.
After the marathon take a week off just to give your body a bit of a rest then in the 2nd week a very gentle build up towards the weekend where a steady 2 hour run should be possible.The following 2 weeks train as per pre Paris then slowly come down again in the 5th week,the final week is again as per Paris nice and easy running.Good luck and let me know how you get on.
Steve