You buy tools so you have them "just in case". So you start out with a Gearwrench or Blue Point tool. Put it in tool box. A few months later it hasn't moved once, but you see a good deal on a Matco one. So, because this is better made, you buy that one too, "just in case."
Or, you have twenty 3/8" ratchets, but not a Facom. So you buy it, use it once, then go back to your F80 every time... But it's good to have "just in case."
Now, I have about 50 screwdrivers in my tool box. Let's say 20 flat, 20 Phillips then some smaller eyeglass repair type things or whatever. Then I have another a locking pry bar box with 5 or so extra long ones, then 3 plastic bins filled with old wood handle, Chinese brands, and older Stanley screwdrivers. Stopped at the pawn shop a few weeks ago and I'm digging through some big boxes of sockets, screwdrivers, etc and it's one of those things everything is $1. So I find a 4" Williams adjustable wrench, then sitting on top of the next box are two black handle snap on screwdrivers. So I wait for the big boss to leave the room and ask the lady, "is everything in this box $1?" Yes sir. I couldn't get the money out fast enough and made sure she never saw those two words on the handles. My guess is someone else found them, asked how much and put them back because the owner probably said $40 or something. That's why they were side by side on top. Plus, they have a glass cabinet for their "good stuff."