LP fill and tank?

[Mandyfiechtner]

Hi all- New here and new to RV life. I am hoping someone can help me sort out some confusion with my LP system. I have track all my lines back to my propane tank but I am confused by the fill location and where it leads. I’ve attached pictures and tried to put them in order.

Is this a secondary LP tank? I can’t for the life of me find anything online to help me identify what’s going on.

The copper line going to my propane tank t’d off this one on the inside, I’ve disconnected all that.

Thanks for any thoughts!! I’ve read these forums extensively for lots of other reasons, hoping someone might know what’s going on