There is a way to use the MS Edge legacy browser with the new MS Edge (Chromium) browser side by side.
Installing the Stable Channel of the next version of Microsoft Edge at the system-level will cause the current version (Microsoft Edge Legacy) to be hidden. If you want to let your users see both versions of Microsoft Edge side by side in Windows, you can enable this experience by setting the Allow Microsoft Edge Side by Side browser experience group policy to Enabled.
To set up the side-by-side browser experience policy:
- Install the Policy Definitions from Microsoft Edge for Business.
- Open the Group Policy Editor (gpedit.msc).
- Under Computer Configuration, go to Administrative Templates>Microsoft Edge Update>Applications.
- Under Applications, double-click "Allow Microsoft Edge Side by Side browser experience".
- Select Enabled and then click OK.
To get detailed information, you can refer to the link below.
Side-by-side experience with Microsoft Edge Stable Channel and Microsoft Edge Legacy
Running Microsoft Edge Legacy side-by-side with the new version is not recommended for regular usage. This configuration should only be used in specific cases where testing with both browser versions is required.