Generally, words with ancient voiceless consonants in the rising tone and those in the departing tone belong to distinct modern tone categories in Hakka dialects like Meixian, Pingyuan, Jiaoling and Wuping. However, there are some notable exceptions. Some words in the ancient rising tone are pronounced in the departing tone and vice versa. This paper first describes the phenomena based on dialect reports. Through geographical and systematic analyses, the author then concludes it is the loss of the lower-register departing tone in the synchronic context of three falling contours that has caused this tone mixture to occur.