Default Systemui.apk

So I decided to do a little more theming to my systemui and I noticed that on my device I have one in system/priv-app(the one I should be theming) and one in /data... Does everyone(with our device on stock) have an additional systemui.apk in the /data folder ? What is this one for? Do I have to modify both? Can this one be safely deleted? Thank you kindly for your time

We cannot teach people anything; we can only help them discover it within themselves.