Most motorcycle riders only own one bike. Motorcycles, like automobiles, are something most people only need one of because, well, you can't drive two of them at once. However, there are some people out there who own more than one car, and there are some who own more than one motorcycle, too. Even though they can't ride more than one at once, there are some reasons why one might want to have two bikes in the garage.
The first is that you may want a spare bike for one of your friends, your spouse, or even one of your teenage children to ride. They might want to try out motorcycling before they invest in their own bike, and having a second one allows you both to ride. Some people also can't quite afford a motorcycle yet but want to ride, so it's very handy to have one you can loan out.
Other people love tinkering with motorcycles. They will often purchase a used or damaged bike and work to restore it. These people may have three or four bikes in the garage, all of them in various states of disrepair. Sometimes they'll buy a cheap one just for parts.
Then there are bikers who want to purchase a new motorcycle but just can't bear to part with their old bike. They've got so many memories wrapped up in that machine that they just can't bring themselves to sell it. Instead, they buy a new motorcycle and keep the old one around for sentimental reasons.
Finally, some people need two different types of motorcycles. They may have one they drive to work every day but want to do some motorcycle racing on the weekends, so they need a cruiser and a racing bike.
