What does the name 2R in the organ file mean?
There are certain virtual pipe organ products that ship with more than one organ file for the reason to provide more flexibility in different loading setups. By default, Inspired Acoustics virtual pipe organs for Hauptwerk version 3 and version 4 use 3 different release sample layers for each note. This means that for the shortest, longer and very long notes have individual release samples. This provides more realism in the sound, but also uses more RAM when you load it. Since Hauptwerk version 3 and 4 provides the ability to load "all" or "first" release layers only, there is no other way to load only 2 release layers of the available 3 than by using a different organ file. This is exactly what the 2R version provides, namely the option to load the organ with only 2 release layers. That provides slightly less realism than the default 3 layer version, but also uses less RAM. If you are working with a sample set with a longer reverberation and the Dynamic KeyboardMass functionality enabled, you can safely use the 2R version without greatly affecting the realism of the sound. By using the 2R version you will save a significant amount of polyphony and RAM.