Back in the 1950's my FIL and GFIL bought 2 outboard motors. They turned out to be consecutive. I'm sure they never even knew it. After both passed my MIL gave them to me. My OB motors are a collection, and thus I have all of them logged in a spreadsheet. Since both were rare and collectable, I was able to trade one of them for 2 others. I didn't need to have 2.
OTOH, I have two sets of consecutive revolvers. In both cases I bought them on purpose and they will always stay together as a set. Just my interest.
The 1851 Navys in my avatar are one of the sets.