Maybe I can shed some light on the topic of a "double maduro." In theory, a 'double maduro' would mean a maduro binder surrounded by a maduro wrapper.
What I learned from speaking to various tobacco growers in Nicaragua and Honduras was that this does not really translate well in the 'practical world.' The reason being that a maduro leaf is fairly thick - works great for a wrapper, but use it for a binder and you're looking at combustion problems.
As such, I believe what you're looking at in the case of a SP 'Double Maduro' is a true maduro wrapper and a connecticut seed binder that has been fermented longer to be "DARKER," however, it would not be considered a true "MADURO" leaf as we've come to know maduro as.
Make sense?