Maybe I am making this too simple, but in your query do you show the join between the two tables? If not, then you will get what you are describing.
Parent info, one side, 10 records.
Child info, many side, 50 records.
If you show the join in the query, then you should get 50 records.
If you DON"T show the join, then it becomes the number of the parent records times the number of child records, 10 x 50 = 500.
HTH