An earth-boring tool comprises a body having a face at a leading end thereof, blades extending from the body and comprising primary blades and secondary blades, and cutting elements on the blades and arranged in groups each comprising neighboring cutting elements. Some of the groups are disposed only on the primary blades in a first spiral configuration. Others of the groups disposed only on the secondary blades in a second, opposing spiral configuration. Methods of forming an earth-boring tool, and methods of forming a borehole in a subterranean formation are also described.