I don't tend to buy many backups.
I have back ups of my beloved Palmer's Cocoa Butter Swivel Stick, but that's only because it seems like whenever I run out, I can't find it anywhere! So I want one ready to go for when my current one is gone.
I have several back ups of my Jordana Color XTend e/l in Blackout. It's one of my fave black liners, and they're always 2/$5 at Walgreens. However, it always seems like if I wait til I run out, they'll be out and not re-stock for awhile. So now I tend to buy 2 everytime I go to Walgreens, LOL!! I think I have about 6 right now...
I must admit I have 3 backups of L'oreal Blush Delice in Sugar N Spice. It's been clearanced at CVS, and then Walgreens here, so I snagged 3 at half price. I just love this color!
I also have extras of my MAC Fresh Brew l/s (one for home, one for my purse), as well as back ups of my C-Thru and Cultured l/g. I don't need them yet, but I swapped for them. I'd like a backup of Prrr as well.
Otherwise, even though I'm tempted, I try not to buy backups unless it's a staple item. I rarely make it through a colored product unless it's a staple..