Nether Portal duplication

Enter nether portal from overworld.  Enter nether.  Re-enter the portal from nether to return to overworld.  New nether portal is created in a different location from original portal.

I would then destroy an obsidian block to the newly created portal, travel back to the original nether portal and repeat the process.  A new portal would be created every time (within the same area; see screenshots).  

I saved a backup of my server/game before the update, reloaded that file and still had the same issues.