I met an exceedingly pleasant woman last week. Bubbly. Friendly. Open. Chatting at a school event, we found we had much in common: kids in the same class, husbands who were off in the corner avoiding chit-chat, a staggering appetite for potluck. We bonded like Bazooka to the bottom of a ballet flat.

But I knew something she didn’t know. I knew how close we came to being enemies. Because the skirt she was wearing, an offbeat green number with a playful bounce and a bewitching shimmer to it, was the very same skirt that was hanging in my closet as she and I exchanged grins and carpool tips. The very same garment I had been planning to wear that night until a last-second outfit overhaul. The very same ring of common pleated cotton that, had we both shown up in it and been forced to schmooze side by side for two humiliating hours, would have caused me to hate this lovely woman’s insufferable guts.

Wow, that looks even more psychotic when you see it in print.

But it’s not a reaction I had any control over; it’s visceral. Doppeldressers, or fashion facsimiles, if you will, tear at the very fabric of a woman’s self-esteem. When we see a lady driving the same car as ours, we feel a kinship with her: Hey! She likes what I like! When we discover a coworker lives in our neighborhood, we embrace the coincidence: Cool! You, too, gave up ocean views for a bigger backyard!

But catch a fellow party guest sporting our beloved newsboy cap, slouchy ankle boot, or — oh no, she di’n’t! — our splurge-of-the-season sailor pants, and (I’ll deny that I typed this, but) someone’s going to wind up with a purse full of Diet Coke before the evening’s through.

To wit: “I wore a really cool coat to see George Clooney at the Santa Barbara International Film Festival,” offered a stylish and normally sweet girlfriend of mine, “and some b*%@# had on the same coat.”

You don’t have to unzip this copycat-yields-catfight phenomenon very far to see what’s causing it. “We all want to be the one who looks the best in the outfit,” my friend confessed. Never mind if most of the women at the party already look better than us anyway; we seem to think that without the visual cue of identical outfits, no one will think to compare us. See, we were pulling off this taffeta bubble dress just fine before we met our “match,” and now that fellow guests can see both of us in the same field of vision, it’s distressingly clear that we had no business buying it in the first place and who exactly were we hoping to fool?

I’d like to blame Us Weekly for fostering this paranoid comparaphobia among sister-strangers. The glossy gossip rag — the same one known for its hard-hitting celebrity-cellulite exposés, mind you — runs an item called “Who Wore It Best,” which juxtaposes the photos of two identically frocked starlets and asks readers to vote for who’s cuter.

But in truth, women were stressing over show-stealing skirt burglars long before Us began running its invasive, demeaning, and thoroughly irresistible photo feature. Our aversion to duplicate dressers goes beyond “Who Wore It Best.” It’s about individuality, self-expression, and the immense satisfaction — indeed, validation — that comes from hunting down, finding, and then (yippee!) slipping into a truly unique item of clothing. Something with character. Something that makes you feel like yourself, only with the volume turned way, way up.

So it’s only natural we should be miffed and disoriented when we spy a similarly clad floozy, er woman, expressing herself in our territory.

My new friend and I remain chummy. I’m choosing to cherish our similar taste rather than curse it. And I hope that’s the way she’d see it, too, if she were in my shoes. Which she’d better never be.