When my wife and I got married, we registered for a set of measuring cups. At her shower, my wife discovered two people had given us sets. The consensus at the shower: Keep the second set; you’ll be happy to have spare measuring cups kicking around your kitchen.
After cooking with two sets of cups for a couple years, I heartily endorse the concept of owning duplicate measuring cups. It’s one of those little things you can do that makes your life much, much easier.
Instead of having to wash a cup in the middle of a cooking project, just reach into the drawer for its backup. Did you toss a cup into soapy water prematurely? Just grab another. Stop trying to measure a 1/4-cup of flour with the 1/3-cup measurer. There is a 1/2-cup measurer permanently in our oatmeal canister because I know I have another one in the drawer. Having two sets is especially useful when measuring ingredients that are sensitive to water, like flour and sugar. Instead of having to carefully wash and dry the cup, just grab a clean and dry one from the drawer.
Want to measure a cup of onions and chocolate at the same time, without washing? (And please tell me what you’re baking!) Get a second set of measuring cups. It’s worth it.