There are 2 obvious places I look for when trying to duplicate an object in Blender, first is right click the object in the Outliner, but no, no option to duplicate this object there, damn!.
Second obvious place is to go to the edit menu, nope, not there either.
Then look everywhere for a hint of an option to duplicate the bloody object.
No luck, frustration, reaction: ask google, and finally find out that there is a specific short cut to do it…as usual tipical of blender.
The problem here is even on 2.8 with all the UI improvements there are still simple stuff like this missing to help out new comers.