You should be careful about duplicate values as they invariably create a wrong result. They are generated due to below operations.

Joins: We know that joins are used to connect two or more tables, but when the joining table has the duplicate values it creates some duplicate values in the resulting table (for example we have table A and table B and we are creating table C. If table B has duplicate values, table C will have duplicate values). If the resulting table value is used in any aggregation then it may show you the wrong value.

Thus while using the joins between the tables you must make sure that the joining table has the distinct values.

You should perform join operation as shown in following figure:

One thing to note here that we didn’t use the Distinct keyword in joining table, because if we do that Qlik Sense will remove the valid duplicate records from the resulting table.