Metallica guitarist Kirk Hammett had no idea his historic 1959 Les Paul Standard — the guitar affectionately known as "Greeny," first owned by Fleetwood Mac founder Peter Green then musician Gary Moore — had an exact twin right off the old Gibson factory floor.

After all, why would he? Just think of the chances. Greeny is one of the most expensive guitars ever sold.

Yet, he recently learned just such a duplicate exists. Even more remarkable is the twin guitar — it has a serial number Hammett found is perfectly sequential with the famous instrument he previously acquired for a reported $2 million — was in the possession of Gibson's brand president, Cesar Gueikian.

"I've always thought of Greeny as an anomaly," Hammet says, "just as a result of the way it looks and sounds and everything it's been through. It's a unique, solitary instrument." [via Guitar World]

But it would make sense that the guitar had others similar to it made by Gibson in the '50s. Still, coming across one likely manufactured simultaneously, and with similar specs such as sunburst finish, seems pretty unusual.

"We realized the two guitars have sequential serial numbers, and our minds were blown," Gueikian marvels.

Greeny's serial number is 9 2208. The twin guitar — Hammett and Gueikian have now dubbed it "Gemini" — is 9 2204. The closeness of the serials on its own is a big find, but don't let the non-sequential digits fool you — they were indeed made one after another.

"I got in touch with [Gibson's head of product development] Mat Koehler and the rest of the team," Gueikian explains. "We figured out that the numbers in the middle are only Skylark amps. So the guitars are sequential twins in terms of being Les Pauls and 'bursts."

He says of the guitars' woods and finishes, "Our hypothesis is that they were probably cut from the same maple billet because the flame patterns are very similar — slightly off — and the mineral streaks are almost identical in the way that they run vertically."

It just goes to show, you never know what you'll find if you look. But does this mean Gueikian's guitar is also worth $2 million?

Hammett will release his first-ever solo EP, Portals, on April 23. His guitar from Metallica's "One" video once sold for six figures. Last month, his Metallica bandmate James Hetfield donated a signed guitar to the MusiCares Charity Relief Auction that went for $25,000 above estimate.

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