Frontend eats changes when opening another workflow from same source as current

### Prerequisites

- [x] I am running the latest version of ComfyUI
- [x] I have custom nodes enabled

### What happened?

I.E., load the workflow from an existing generation. Iterate on it for a while. Think "_Hmm, what was that setting in the original workflow?_" Drag the original file into ComfyUI again (which previously would open a new tab). Instead, it overwrites all the changes in the current tab (tabs in ComfyUI, not browser tabs).

### Steps to Reproduce

1. Load a workflow from a file by dragging it into ComfyUI.
2. Make changes to it.
3. Drag that same file into ComfyUI again. Lose your work.

### How is this affecting you?

Crashes ComfyUI completely

### ComfyUI Frontend Version

1.43.10

### Browser

Firefox

### Console Errors

```javascript

```

### Logs

```shell

```

### Additional Context

_No response_

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-10766-Frontend-eats-changes-when-opening-another-workflow-from-same-source-as-current-3346d73d36508198accce8ff6c4100a1) by [Unito](https://www.unito.io)