A dual SIM phone allows the user to run two lines through one device. You could have one business line and one line for play. The HTC Butterfly S would be a sequel to the HTC DROID DNA at Verizon and might not come to the U.S. for some time, if it comes at all. After all, the HTC One, which is the Taiwan manufacturer's flagship Android model, is expected to come to Verizon on August 1st. And if there is a sequel to the HTC DROID DNA, it won't be the dual SIM model which is a feature that has not really been popular in the states.
source: @leakschina via SlashGear