Always use Synchronize with Central (SwC) immediately after loading new families or types (or duplicating system family types). Don't place any instances.
If we can't get a single person to manage this loading then using SwC immediately afterward will increase the odds that a warning message will appear as soon as the transaction is completed. This does assume that we all develop this habit. If the warning appears than we need to examine the new family(ies) and or type(s) in the Project Browser and resolve the issue.
The goal is to avoid creating the duplicates and even more importantly using them in the project.