Yes on the basics like good undergarments, shirts/tops and pants. Not so much on suits and such, though I'm getting to the point in my life where if something fits, I'd rather buy multiples and not have to shop any more!
All the time, and in many things. Shoes, just bought two pairs of slip on sketchers in two colors. Nightgowns- when I find a comfy flattering one I buy as many colors as I can find. Bras, too. Tees, jeans, sweaters as well. Sheets and bath rugs too. Pretty much in everything. Ok, I only bought one Vitamix. Not too long ago, I bought four Rebecca Minkoff Cupid Satchels (killer sale). The perfect bag.
I'm guilty of buying second pairs of shoes/boots to have "in reserve" when the originals wear out.
My favorite boots are Naturalizer in a style no longer available. I bought black and brown in both the smooth leather and the suede. And then I bought back ups for both colors in the suede. Now, I did not at any time pay the full 179.99 price! They were all bought via the internet from Zappos, Amazon, ShoeBuy, etc. at greatly reduced prices. But I shouldn't need boots for awhile.