Bug? Armature and lights come back after being deleted

I have an armature and a bunch of area lights that I keep deleting, I save, reload the project, and they are BACK!
I selected orphan data after deleting them and did “purge all” and after this they come back. What does it mean?
I’m using Blender 2.79
Any clue?

Sounds like a glitch/feature in the Purge All, which you should not need to do. If they’re actually orphaned then if you save and load the project then they should be gone when you re-load.

If you’re using 2.79b, you can try one of the 2.79 experimental builds from builder.blender.org/download and see if the behavior has changed in the last 15 months since 2.79b came out.