They may not be using Lorann flavors. There are several flavor companies, like FlavorArt, Capella, and others. The same flavor from a different company can and often does taste different. Pralines and Cream from Capella is entirely different than from Lorann. Some
juice companies add some ethanol to their mixes. Even VG from different sources can have a slightly different taste. %s of each component are also important. And some tobacco juices have very complex mixes of flavors that would be hard to duplicate from scratch.
In the beginning with DIY, I would simply be shooting for making juices you like, rather than matching a
juice you have bought, which is advanced even for someone who has been doing DIY for a while.
Additionally, and perhaps most important, what is the company, what is the flavor, what is the PG/VG ratio of the
juice you are trying to to duplicate, and what are the %s of the other components in the juice? Some companies print this on the bottles, some will tell you in an email. Many will not know themselves if they are getting the juices from China. A bit more specific info as to what exactly you want to duplicate would be helpful for us.