Rear window defogger cables

[carikower]

Hi, I have an aygo 2014 and noticed that had some of the lines in the defogger grid had been scratched and stopped working.

Luckily, I found a glass replacement cheaply and bought it, but I realised later that it came with two cables connected to it (in my previous glass I had just one cable on it on the left). Photo attached of the old one on the car and the new one on the floor not yet installed. 

For my new window I wonder if I still need to connect both cables or whether with the same one cable connected as my previous window it should be fine?

I'm assuming 2nd cable is ground and would go to chassis, but as my previous window didn't have a 2nd cable on it, then probably it isn't needed? 

Hope I'm making sense.

Thank you