It is definitely not the first 2 ways earbuds Panasonic ever made. The dual driver series started with HV70 on 1986, then HV75 and HV100 around 1987, followed by HV80 at around 1989, with HV600 on 1991 as the last model. Trying to find any earlier models than HV600 is probably just as hard as winning a jackpot. There is however a hidden dual driver model called HJ329 that was not independently released as a standalone model but only as an exclusive stock earphone for higher end Panasonic discman and MP3 player way back in the early 2000s. You can still find it on Taobao sometime but it is not nearly as good as the fame HV series. One fun fact is the HJ239's design is what inspired the Rose Mojito (and Masya to a lesser extent). Second fun fact is HV600 is not a true 2 ways design - the treble driver is not an driver an all, but more of a passive radiator.
Only difference are the color of the housing and the cable. Otherwise they are the exact same model.
