fix issue #53 - client will receive duplicate messages when overlapping subscription
fix issue #53 - client will receive duplicate messages when overlapping subscription

shaominghaoo/emqttd,sureddy/emqttd,lianghaivv/emqttd,Inner-room/emqttd,tempbottle/emqttd,gxbllm/emqttd,jfjalburquerque/emqttd,yocome/emqttd,santuoshi/emqttd,AcmHacker/emqttd,joaohf/emqttd,neviim/emqttd,fsxchen/emqttd,yangchaogit/emqttd,fengshao0907/emqttd,yanyanqin/emqttd,mickelfeng/emqttd,janshahid/jmq,guidao/emqttd,codertrack/emqttd