Powered Rail Duplication

Yes, you're probably not new to the concept. You're probably sick of seeing it. The dreaded rail-duplication glitch.

Steps:
1] Make the advanced rail react to a lot of updates at once.
2] Move the rail somewhere that also has a lot of updates happening, with no block underneath (so it breaks).
3] Pick up freshly duplicated rails.
4] Make it rain rails.

The original report for this was last updated two years ago, and I assume is forgotten, so I just wanted to put this here for you to see. I know that it's really difficult to fix because of the LARGE amount of updates advanced rails have to check for. It was almost fixed somewhere in the 1.9 snaps, but an extra update to them causes the bug again.