Not sure if AA will protect a second itinerary as a Gold or Plat. I know from personal experience as an EXP that AA will book me on a later flight (keeping the original as well) if it looks like a misconnect is likely. In the event that the MAD-PHL flight is delayed, it can’t hurt to ask. Even without status AA sometimes will be proactive and if a misconnect is likely it will rebook you on the later / connecting itinerary. It just won’t keep the original itinerary as well. If you somehow wind up making up time and getting through immigration quickly, you can always ask at the AA counter after immigration to put you back on the earlier flight.

As I said above and JJeffrey as well - 1:40 is doable. Though PHL is my home airport and I rarely connect there, I have in the past flown LHR-PHL-LAX/SFO and made 45 minute connections. Though those were T A-West to A-East or B/C - you’ll be going to F (there is a shuttle). I wouldn’t recommend a 45 minute connection (I don’t think AA allows it) in your case, but it worked for me. I also have a place to stay if it doesn’t.