Modular design. One can have multiple instances of the same sheet. (I use that all the time.)
It never broke something for me. Can you give more information what exactly happened such that other people can learn from your mistake? (In other words: You have me worried right now.)
Always bacup before you do that! (git or svn is your friend)
I suspect that anybody who has worked with any kind of CAD, CAE or EDA tool for more than 6 months has experienced something similar. The most practical solution to the problem is “backups” or “archives”. I have trained myself to create fall-back copies at least twice a day when I’m actively engaged with a project. The automatic backup feature in many programs is of limited help, unless it lets you retain those backups at least 3 or 4 deep.
(Consider: You set the automatic backup to operate, say, every 15 minutes. After you do something stupid, you typically spend the first 10 minutes just verifying that you did something stupid. Then you spend 10 minutes trying to un-do your stupidity. Then you spend 10 minutes trying to calm down, cover up, and deny your stupidity. By this time, the automatic backup feature has preserved your stupidity twice over.)
In exchange for a serving of my preferred malt beverage, you can be assured that neither your co-workers nor your supervisor will learn of your mistake from me.
So, after giving it some thought, I think I know what started me down the rabbit hole.
I created the first sheet (1 sheet) then block copied it (2 sheets).
Then block copied those two sheets (4 sheets).
Then block copied one of those sheets (5 sheets).
Then I renamed the sheets… DOH…
So, if one does NOT do ^^^THAT^^^ it probably works as expected.
Forty-four years ago this month, my wife’s aunt started arranging for us to meet. Supposedly, my sense of humor reminded her of her brother-in-law (my wife’s father), and this in turn suggested compatibility between my wife and I. You’ll have to ask my wife for examples of dumb jokes I’ve pulled on her across almost 43 years of marriage.
A good example of why you should use revision control. Nowadays I don’t start any serious project without revision control. It also helps that all kicad files are text based.