Quick answer: Unity Input System rebind allowing duplicate bindings (two actions on the same key)? Default doesn't check conflicts - implement custom conflict validation.
Player rebinds Jump to E. Doesn't know they also rebound Interact to E. Both fire on press.
Check before applying
On rebind completion, iterate all actions; reject if the new binding conflicts.
Or use a custom rebind dialog
Dialog shows conflicts; player resolves before save.
Validate after restore
Loaded bindings: validate; warn on conflicts. Restore + manual resolution.
“Rebind doesn't validate. Validation is your responsibility.”
Build a rebind conflict checker as a one-time helper. Reusable; the bug class disappears.