Why does one button press do an action twice?

Because the input is being handled in more than one place, or both via an event and via polling, so the single press is processed twice. Or a once-per-press action is being triggered every frame the key is held rather than only on the press event. Audit for duplicate handling and ensure the input is processed exactly once, on the press event for actions that should happen once per press.

How do I distinguish a press from a hold?

Handle the press event (the moment the key goes down) separately from the held state (the key being down across frames). Trigger once-per-press actions (jump, select) on the press event so they happen once, and use the held state for continuous actions (move, charge). The double-input bug often comes from triggering a once-per-press action every frame the key is held instead of only on the initial press.

Why Does My Game Register Double Inputs?

Q: Why does my game register double inputs?

Because a single input is being processed more than once: the input is handled in multiple places, or both via an event callback and via per-frame polling, so one press triggers the action twice. It can also come from re-triggering a once-per-press action every frame the key is held (not distinguishing press from hold). The fix is to process each input exactly once, on the press event for once-per-press actions.

Quick answer: Your game registers double inputs because a single physical input is being processed multiple times: it's handled in more than one place, or processed both via an event callback and via per-frame polling, so one press triggers the action twice. It can also come from re-triggering a once-per-press action every frame the key is held. The fix is to process each input exactly once.

Double inputs (one press doing two actions) undermine the precise control players expect, a single jump press jumps twice, a menu selection activates two items. It's about processing the same input too many times, and it has a clear fix.

Why Double Inputs Happen

A double input occurs when a single physical input is registered as two (or more) actions. The usual cause is processing the same input in multiple places, the input event is handled by more than one piece of code, or the input is processed both via an event callback and via polling each frame, so one press triggers the action twice. It can also come from not distinguishing a press from a hold (re-triggering each frame the key is down when you meant to trigger once on press), or from input events delivered more than once.

The signature is one input doing the action twice (or repeatedly). The cause is almost always the input being handled more times than the player pressed it.

How to Diagnose and Fix It

Reproduce by pressing once and seeing two actions, then audit for duplicate handling: is the input handled in multiple places, or both by event and polling? Is a once-per-press action being re-triggered every frame the key is held? Bugnet captures reports with context confirming which inputs/contexts are affected, though this is usually reproducible locally.

Fix by processing each input exactly once: ensure a given input is handled in a single place, don't process it both by event and by polling, and distinguish press, hold, and release clearly (trigger once-per-press actions on the press event, not every frame the key is held). See our guide on fixing double input and stuck keys.

Double input is processing one press twice, handled in multiple places, or both event and polling. Process each input once, on the press event for once-per-press actions.