I do it, but usually only two colors. (I do however have a bunch of turtleneck sweaters.)
My daughter-in-law taught me to buy multiples. her rule is to buy at least one in a color you don’t normally wear. I buy bras in multiples when I find one that I like and fits well, usually all in nude shades, maybe one in white or a cute color or print.
I don’t know if it’s common overall, but I do that quite often.