I'd be tempted to be embarrassed by this little quirk, but it's really not that harmful. And I can stop buying doubles anytime I want.
No, seriously, I can.
Sometimes, truth be told, I don't even buy two of the exact same model. I have two different kinds of olive oil in the pantry, for example, for different uses. And two kinds of balsamic. And two, well, fine, three kinds of sugar. I've got white granulated, light brown, dark brown, demerara, confectioners', superfine, turbinado, and muscovado. That's essentially three kinds, or it's close enough. I counted fast. And I'm rounding down.
Muscovado is my darling-of-the-moment. With a deep, seductive richness, it's sweet in an almost guttural way. I know that might not make sense, but here's an analogy: if there's a shallow tidepool, muscovado won't be swimming in it. It's too serious. You'll find it swimming way, way down, with all the pretty corral and sea anemones -- where sunlight barely reaches, where mermaids fear to tread.
If you want more technical info, Mark Scarbrough offers a nice write-up of muscovado on his blog Real Food Has Curves and The Kitchn has an info-packed discussion of muscovado, too. Also, for general background, I wrote a piece on unrefined sugars for Nourish Network back in December.
You can find muscovado sugar in many kitchenware shops, and in larger grocery stores with a decent baking aisle. Go easy at first. Sprinkle it on your oatmeal, or on a grapefruit half, so you can really taste it and experience its flavor and texture without distraction. Don't text while you eat it, and don't bake with it the second you open the package. Or packages.
Since, duh, you'll probably be buying two.