Yes, it is possible to just model one and copy, but even that is not necessary, as the "digital master" could have only one, and the rest could be done in molding process.
If they were "mirrored" I could copy one and mirror it digitally, that can't be done using molding rubber.
The right way would probably be to model basic shape of the one, copy and then do some variations, so they are not 100% the same - at least some scratches and texture - that I'm going to do.