Site diversity is considered to be an effective technique to overcome potential large rain fade margins in satellite communication links. In addition, because of the expected orbital and frequency congestion, the aggravation of the signal leakage from an adjacent Earth-space system operating at the same frequency due to potential differential rain attenuation will be considered as a dominant source of interference. In this paper, an existing method to predict the differential rain attenuation statistics with respect to a double-diversity system is properly modified after assuming a more realistic model for the rain height. Some simple regression-derived formulas appropriate for use by the system designer and concerning both existing and proposed analysis are also presented. Further, the difference between existing results and the ones deduced from the use of the modified procedure for various availabilities and frequencies is examined, and some useful conclusions are derived.