The choke housing seal for the vacuum supply is not rubber, it's hard plastic.
The seal for the shaft is a rubber lip seal. There is another one in the choke housing. Both should be replaced during rebuilding as the rubber goes bad over the years and you can get a leak in the system.
If an electric choke is being used, you can leave out the rubber seal in the choke housing, it is not needed, but still install the one between the housing and the carb to seal off where the shaft goes thru.....Cliff