Whether you only speak a little Korean or you’re a native speaker, it’s not unusual to have to clarify which station you mean when talking about these two stations due to how similar they sound. What made it even worse is the fact that they are both popular entertainment areas for university students and there is also a suburb named Sincheon-dong on the other side of Jamsil to where Sincheon Station is located.
It seems Sincheon residents finally got sick of this and asked that it be changed. Following a vote from a selection of names including Sinjamsil Station (신잠실역) and Jamsil Jungang Station (잠실중앙역), the name that received the most votes and will be used as the new name is Jamsilsaenae Station (잠실새내역).
As for the meaning of the new name, the first part is obviously from the area of Jamsil which the station is located in. The second part of the name “sanae” is actually the pure Korean version of Sincheon (신천) which is made up of “new (新)” and “stream (川)” in Hanja aka Chinese characters.
I personally think they could have just called it Saenae Station as there are now three stations with Jamsil included in the name all on the same line: Jamsilsaenae, Jamsil and Jamsilnaru. Nevertheless, hopefully the change will mean less people getting a taxi to the completely opposite side of Seoul by accident.
The new name of Jamsilsaenae Station is expected to come into use a month and a half later. It will probably still take a while for people to adjust to the new name as always but as signs and subway maps change people I think people will forgot the old name faster than you think. Who remembers what Jamsilnaru Station used to be called?