Duplicate Stamps and Specific Stamps
The Stamps system was built and implemented with the idea of bringing a long-term and challenging aspect for not only the collectibles enthusiasts but all Station Managers. This can result in players receiving a lot of duplicate Stamps; especially when they are targeting Jobs that reward Stamps.
Do not worry, duplicate Stamps are always transformed into keys for you to spend.
When players have very few Stamps needed to complete a particular Collection, it might be more time consuming to obtain those missing Stamps.
Rest assured, the system is functioning correctly while maintaining its long-term challenge. Keep on completing Stamps Jobs; remember, Side Jobs can reward you with a Stamp from any Region and not only the Region of the particular Job.
Players who wish to collect Stamps from a particular Region can take a look at their Side Jobs and see what Side Jobs have Region-specific Stamps included in their rewards. This is indicated with the Region's flag in the Stamp.
Also, the Specialized Stamp Event regularly appears in the game giving players a chance to target missing Stamps more easily while maintaining the collecting aspect of the feature still making it valuable and not easy to collect them all.