I have a dual SIM mt6589 based Android 4.2.1 phone, and I have no idea where the apps are getting installed.
My phone has an Internal SD card(built in), An External SD card and something called Phone Storage(/data ??)
Anyway the apps are supposed to be saved to my External SD but they get saved to Phone Storage.
Screenshots (click images for larger variants)
Also the option move to External SD card is greyed out(It was available before!!). My vold.fstab file
dev_mount sdcard /storage/sdcard0 emmc@fat /devices/platform/goldfish_mmc.0 /devices/platform/mtk-msdc.0/mmc_host
dev_mount sdcard2 /storage/sdcard1 auto /devices/platform/goldfish_mmc.1 /devices/platform/mtk-msdc.1/mmc_host