i bought three new locksets for my house and had them keyed the same at the store so I could cut down to one key there.
I made copies of the truck and car key then melted the plastic crap off the ends to shrink them down.
Then for the rest of my tools and such I bought a set of keyed alike locks so that cut down to just a couple keys there.
Some keys like the new GM ones have both sides matching. I've been told you can cut one key with the patten for one vehicle on one side and the pattern for another vehicle on the other side to make one key open two locks depending on which side is up when you insert it.