No, the amount is held in the project table. So in SQL I can notice that there is only one projet with its amount in the projects table. In a SQL query, I select both (project and amount) only from the projects table. There are 2 records for this project in the result table so (by sql) the result is doubled if I join this result table. And That make sens. But in Qlik, the chart has been build only on project number (coming from projects table) and sum(amount) (expression) coming from projects table as well. In this case, doubled does not make sens.
The key field i.e. 'key_project' should not be used anywhere in the front end as a best practice. Because it is a key and connecting 2 tables which can have different frequencies. The solution is to count the projects by renaming the Project column from Table 'Projects'.