Samsung SH-S223B LE diode and power button PCB panel?

Hi.
I have a question about something what i found when i dismantled my Samsung SH-S223B drive because i had a problems with “rusty” sound after closing the drive door. I solved my problem with “rusty” sounds by changing the rubber belt on the closing mechanism with a capstan/idler belt for tape recorders and by lubricating the rollers with a few drops of oil, and now the drive works as a new. :clap: I also changed green le diode with a blue ultrabright le diode. But the strange thing what i found is a probably a place for a second LE diode which share one same condutive pathway with a factory installed LE diode as you can see : http://img688.imageshack.us/i/14042011739.jpg and http://img62.imageshack.us/i/14042011745.jpg :eek:
My question is: for what purpose is that, why, does exist drives with two LE diodes, while it work if i install there a LE diode, is that LE diode maybe for writing, were another is for reading (if it will be installed) ? :confused:

Thanks in advance for your answers and i am very sorry if i posted my question on the wrong part of the forum and also i am sorry for my bad english. :o