no two brushes are identical, you said so yourself. this means that quality can differ, even among real brushes. since they are made out of actual animal hair, the quality, thickness, and overall construction of each and every brush is different, and therefore, comparisons can be misleading, even among completely identical, authentic brushes. the size of the 129 can make it easier to spot differences. the silver numbering comes off of ALL of the mac brushes, sometimes sooner, rather than later. for future reference, if the silver lettering coming off bothers you, go over it with clear nail polish when you first buy the brush. i know it sucks that you have to do that, but the lettering coming off is an unfortunate characteristic of mac brushes (real ones). i have 30-some mac brushes, all full-size, authentic, and purchased from freestanding stores, and they have almost all lost their lettering. both brushes you have look authentic, i find it difficult to believe a store or counter would sell a fake brush. its almost an impossibility, and its certainly quite improbable. i have 3 187-brushes and they all are different. it's really just the nature of the cosmetic brush.