I'm not a met but I heard the explanation on CNN

The system off of the southeast Atlantic coast actually *is* two distinct low pressure areas, and thus, two invests would be warranted. They won't BOTH develop (knock on wood), and I would *think* the fact that a second low has developed (the northernmost low developed overnight, according to the NHC's TWO), that would indicate that the first low is less likely to develop.

Bay of Campeche system is too close to land, and the Atlantic fish-swimming system is not looking very impressive this morning, to me.