Behind schedule tasks - I'm confused
 

Can anyone explain to me why when I click the "Move behind-schedule tasks to later dates" it actually creates another duplicate task entry below the original with a #<number increment> to the task title? And more importantly, can I stop this behaviour so that it just moves the dates of the original task and doesn't create additional # tasks?

I find it strange as well as illogical and my project plan just becomes cluttered with effectively duplicate entries. Maybe I'm not following a proper project management principle here but regardless, I find the way it does it not to my liking.

Can anyone set me straight here?

Cheers