Running more than one CueCart

How CueCart behaves when you open files or run more than one copy.

Sharing · Updated 2026-06-30

Most of the time you'll run a single copy of CueCart, with one Set open and ready to play. That's the default, and it's the right setup for the vast majority of shows. This chapter covers what happens when a second copy comes into play — whether you double-click a file or deliberately run two windows at once — and how CueCart keeps your show safe in the process.

One copy by default

By default, CueCart runs as a single instance. If CueCart is already open and you double-click a .cuecart file (or another CueCart file) in Windows Explorer, CueCart doesn't open a second window. Instead it brings the copy you've already got running to the front and opens the file there.

This is what you want most of the time:

• You always know which window is live.
• There's no risk of two windows fighting over the same audio device or the same show.
• A stray double-click never spawns a duplicate mid-broadcast.

Allowing more than one copy

Some advanced setups genuinely need two CueCart windows at once — for example, an operator running separate shows side by side. For that, CueCart has an opt-in setting that lets multiple instances run together.

You'll find it under Settings → Instance, as Allow multiple CueCart instances. It's off by default, and the change takes effect the next time you launch CueCart:

• Off (recommended) — a second launch reuses the copy that's already running, exactly as described above.
• On — a second launch starts another CueCart process with its own window, running alongside the first.

Unless you have a specific reason to turn this on, leave it off. The single-window default is the simpler, safer way to work.

Set lock protection

Whether you're running one copy or several, CueCart guards the show with a Set lock. When you open a Set, CueCart takes an exclusive lock on that .cuecart file. While you hold it, another instance can't silently edit the same Set underneath you — so two copies can never quietly overwrite each other's work.

The lock is automatic. There's nothing to switch on, and you won't notice it during normal use. It simply means the Set you have open is yours to edit, and it stays consistent no matter what else is launched on the machine.

CueCart also tidies up after itself. If a previous session ended unexpectedly — say after a crash — the leftover lock is recognised as stale and cleared the next time you open the Set, so you're never blocked by a copy that's no longer running.

Linked playback & looking ahead

When you run more than one copy on the same machine, you can link their playback: turn it on and pick a coordination action (Status Only, or Stop Others) and a coordination group so copies don't talk over each other. Coordinating copies across different machines builds on this groundwork and is coming in a future update.

Related pages

• Sets — opening, saving and managing your .cuecart show files.
• Settings reference — every setting, including the Instance options.
• Packages — bundling a show to move it to another machine.