It's a good question. I think about this. I really don't care at all now, and even enjoy it. BUT my oldest, dearest friend hated - just hated - being copied. In high school, maybe because I took her word for it, I didn't like it either.

On the other hand, if someone did it all the time, I'd probably be annoyed at being shadowed like that. I'd want the person to get their own life.

I love seeing the same item on a number of fabbers. I've learned a lot more from this, than seeing items on the typical model in an ad. And I find it really amazing when the exact same item looks wonderful on women of many different body types...thinking of the VC tube skirt for example.

A few years ago I realized that our next door neighbor was copying our front yard landscaping, item by item. If we put in a boxwood hedge, they did too, etc. At that time I was really into gardening, and put a lot of mental energy & creativity into our design. I tried to keep a sense of humor, but it was difficult.
Now they don't garden at all, so the problem is over thank goodness.

This is a good question. To be perfectly honest, my style world is all about what's on the internet. YLF, Pinterest, other blogs. I live in a poor, small town with no style to emulate or to be inspired by, that's why. Save for the cowboys and construction workers who've got something cool going on (unintentionally).

This means that if I see an item all over YLF I become saturated with it. I might like it a lot but if I see it frequently, the dopamine rush of "new" wears out and I lose interest in the item. For that matter, I lose interest in my own clothes easily as well. The item has to have some other redeeming aspects to make them trump "new" -- for example, if it is good quality, has good fit, or a nice color on me -- I don't get sick of it as easily. ETA - I have some outfit formulas and pieces like my Report Marks booties that are good examples. I've seen them on myself and other forum members and haven't tired yet because they function well and look so good.

I think this aspect of my personality/brain keeps me from twinning a lot, anywhere. It is closely associated with the part of the brain that enjoys the rush of shopping.

I don't mind at all when it's individual pieces, like the VC skirt or the Spiegel jacket or whatever. And taking inspiration from another's outfit is fine too. I'd be flattered if someone was inspired by me. But if someone were to copy me by buying my entire exact outfit... Yeah, I'd find that creepy whether IRL or online to be honest.

Although I think my style would be pretty hard to copy exactly, so I'm not particularly worried about that happening.

I do think that distance plays a role here. Since being unique and creative is important to me, I get a little turned off if I see a million people IRL all wearing essentially the same outfit or item. (this happened today, actually. Apparently there is a uniform consisting of plaid shirt, skinny jeans, and tall cognac riding boots to go apple picking/wine tasting in in new England! I was wearing something different, thankyouverymuch.).

Luckily I don't know anybody IRL that dresses like me!

Truthfully I would be delighted to live close enough to try more things I see here. If someone close to me (physically) copied my every purchase I would be bothered, but I love YLF twinning!

I think of YLF as a group of very inspirational ladies.
I love the idea of twinning, not as an exact replica, but as inspiration to style something a little differently, try something new or to even see someone wearing what you have already have, a kindred spirit.
I used to buy magazines for inspiration, not any more, real life inspiration is much better in my book

I have to agree with a lot of posters above that it depends on the situation. Personally, I'd be thrilled if someone got outfit inspiration from me. But, if someone was constantly posting the exact same outfits I wore, like with your friend's workout buddy, that would be pretty creepy.

It seems like a lot of the items recommended on this forum that bring out the lemmings are just good basics, i.e. the Halogen pencil skirt, the Brooks Bros. button down, Sam Edelman booties, etc. They're not statement pieces, but building blocks which each person uses to create their own statement. Those don't bother me at all.

Copying color schemes and general silhouettes doesn't bother me...in fact, I think it's cool to see variations on a theme.

It would, however, be disconcerting to see someone wearing the exact same items head-to-toe.