Joining two meshes filips normals on one side. Bug or feature 2.75?

When I join two meshes it flips the normals on one side:
I’ve not run into this in previous versions of Blender.



It has always worked this way. Just flip normal on the dup’ side. Just one of those things.

seen this before many times

but is it a bug or normal?

happy bl

well this time when I set the normals in Blender it reverses in any app I export an OBJ to.
I’ve never seen that.

I have noticed this as well, with 2.73. I have to take the combined object into edit mode, select all, and recalculate the normals. Seems to happen whenever I combine an object with a mirrored duplicate.