Often this is because most of the stack trace is the same but one or two lines differ resulting in the creation of multiple issues.
Sentry groups issues together based on the Grouping Algorithms shown here. To see why similar events are being grouped into multiple issues, go into issue A, select the Similar Issues tab, and click on the
Diff button next to issue B.
You can also view the EVENT GROUPING INFORMATION at the bottom of the issue details page.
To override the current grouping behavior, you have some options: