I've weeded out duplicates, and sell them off. I've been doing this for about 2 to 3 years, I think I may have had somewhat of a hoarding problem. The posters that say they have a plastic tub or ziplock bag or 60 pounds of duplicates are all right. I have probably 1500 pounds of duplicates, and that's after I've sold easily 1/2 to 2/3 of them off already. I went through my main box again a couple months ago and took out about 600 wrenches and other tools that were redundant.
I'd highly recommend getting rid of duplicates, unless you do something that breaks tools frequently; then I'd keep duplicates of that tool. I break probably less than 5 tools a year; definitely not worth keeping duplicates of everything. The space duplicates take up and the effort to own them, store them, etc is not worth it in the big picture.
However, how I define duplicates may not be the same as you. I have 2 or 3 combination wrenches of each size, both SAE and Metric in my main box. I also have box end, open end, angle wrenches, short wrenches, ratcheting wrenches. In sockets, I have regular and deep in all 3 drive sizes, plus impacts. Ratchets, I have about 30 in different sizes and configurations. Screwdrivers, several of each size in different configurations. About 50 pairs of pliers. So, if I break something, there's automatically backup there. Plus, I have a road box that has a pretty comprehensive setup also.
If you really feel a compulsion to store duplicates against the chance of breaking or losing something, box them up and put them in low access storage, so you don't have them in your way all the time. At least get them out of your normal tool space so they're not interfering with finding other stuff.
