Some publications may belong to more than one database. When a user performs a search and a publication's articles are part of that search results, retrievals of that publications will be recorded against a specific database.
ProQuest has a database ranking system. If the entry point of that user includes databases that include the same publication then retrievals will be recorded against the database that has the lowest "Product ID". Thus, retrievals would be recorded only once. There's no double counting or an inflation of usage.