No, you are wrong. This was not a part of bug MC-59471 at all, if you look at the bug report, it isn't mentioned anywhere.
No, it is not a duplication glitch. It was used with one, but the duplication glitch has been patched now. However, this functionality has wrongly been patched as a bug, even though it isn't.
This is intended behavior, the string is supposed to stay attached in the 'disarmed' state, where walking over that disarmed string will not give any redstone signal. It is a feature coded in by Notch. The string is supposed to break after the second time, or the first time with anything that isn't shears. This has been mistaken as a bug.
Shouldn't be fixed, it's a good bug that helps people get geared up faster and build what they want in their worlds, instead of spending hours upon hours grinding. Minecraft is a game about building what you want, not spending all your time gearing up.
Please do not mark this bug as invalid, it is not. This bug causes tripwires to be impossible to be put into the disarmed state, and should be actually fixed instead of being marked invalid.