This is almost certainly the result of a many-to-many relationship in Power BI. In Power BI if there are connections between two (or more) tables that evaluates to a many-to-many relationship then Power BI is unable to make a distinction between any two rows and instead will project the same value for any given row placed in a visual.
Here's an easy way to visualize this:
Table 1 Table 2
Product | ID AmountSold | ID
Widget 1 10 1
Smidget 1 20 2
Gidget 2 5 1
When you join these Power BI can't tell the difference in Sales between Widget and Smidget because they have the same ID. As far as Power BI knows Widget could have sold 0 and Smidget sold a total 15, or Widget sold a total 5 and Smidget sold a total 10, etc.
As a result of this many-to-many relationship Power BI panics and evaluates them to be the same result because it can't determine what is right. Widget and Smidget both sold a total of 15:
Visual
Product | AmountSold
Widget 15
Smidget 15
Gidget 20
You're experiencing the same issue in your data model, although it is undoubtedly a much more complex relationship than the one I just laid out. You need to go back and determine what table(s) are experiencing a many-to-many relationship and fix the issue. Based on the information you've provided it can't be done from here.