If there is an Interactive filter (reference, multiple) on a dashboard and that filter has one or more default value, clicking on 'Reset Filters' adds the default items + whatever is selected on the combo dropdown at that time.
Steps to Reproduce
In an OOTB Instance
1) Navigate to 'Self-service -> Dashboards'
2) Open the OOTB 'Incident Management' dashboard
3) Click on the '+' sign to add a new widget
4) Select 'Reference -> Incident Assignment Group - Multiple'
5) While still in edit mode, hover over the new widget and select 'Edit content' (Pencil icon)
6) Add any 3 groups to the Default values field
7) Save and return to the dashboard
8) Select an additional group from the filter so that there are now 4 elements selected
9) Click on the hamburger menu and select 'Reset Filters'
Only default values should appear
The default values + the last selected value appear.
There is currently no workaround for this PRB
Related Problem: PRB1440589