Quick answer: Unity Input System composite action triggering once per modifier binding? Composite uses multiple bindings as one - check Modifiers in inspector and use ButtonWithOneModifier.

Ctrl+S binding fires the action twice: once for Ctrl, once for S. Should fire once for the chord.

Use ButtonWithOneModifier

Action binding type = ButtonWithOneModifier. Fires once when both keys are held; ignores individual presses.

Or set Interaction = Press

Default interaction sends performed on each binding change. Press interaction debounces to one fire per chord.

Verify with the input debugger

Window > Analysis > Input Debugger. Shows performed/canceled events per binding. Double-fires are visible per-frame.

“Composite bindings are syntactic sugar over multi-binding rules. The rules need to be right.”

For keyboard-heavy games, treat the input action asset as code. Code review it; document binding intent in the action's note field.