I can't say enough good things about a multiple clipboard manager. Not only is it useful to copy/paste multiple items in sequence, but it's a game changer to be able to quickly retrieve a code snippet, or URL, or CLI command you used recently; and/or, to trivially stash one just in case you'll want it later. (Primary downside: using a computer without multiple clipboards feels broken. What do you mean it "forgot" the thing I copied five minutes ago?)
My weapon of choice these days is LaunchBar [0]. Despite the clipboard history feature being bolted on to otherwise unrelated functionality, I love the low-friction keyboard shortcut: Cmd-\, arrow-down to the chosen item, release Cmd to automatically paste.
[0] https://obdev.at/products/launchbar/index.html