It isn't intended. I can confirm. It happened to me. I was just about to report this bug when I saw this report.
The same thing can be achieved with wooden trapdoors. It's nothing special, but I would like this 'bug' to remain as a feature.
I confirm. It happened to me many times. Very annoying. PLEASE FIX!!
This happened to me in 14w06b. In the output cell it says it's the same scale, but when I Shift-click, it gives me the correct scale.
It is quite self exclamatory. There is nothing more I could explain or post to help.