How to Install Two MacOS Versions On One Computer?

• Author: Vladimir Artiukh
• Editor: Oleg Afonin
• Updated: 5.03.2025 15:13

Read this article to find out how to install two versions of MacOS operating system on one computer. How to install a beta version of MacOS 15 Sequoia as a second operating system.

Contents

• Step 1. How to get a beta version of MacOS for developers
• Step 2. How to partition your hard disk
• Step 3. How to install two versions of MacOS on one Mac
• Additional method. How to install two MacOS versions on one computer with the Recovery menu
• Conclusion
• Questions and answers
• Comments

You may need to have two operating systems if you don’t want to disrupt the stable work of your main system, but you also wish to try out the new features in the latest beta version of MacOS. This is especially relevant for developers and IT enthusiasts who want to be the first to explore the new developments and check them out.

Besides, installing a second operating system allows you to run old apps which might be incompatible with the new versions of MacOS. This way, you’ll be able to enjoy new features and at the same time retain access to all the necessary software, creating the best conditions for steady workflow and exciting experiments.

In this article, we’ll explore how to gain access to the beta version of MacOS 15, and how to install it as the second operating system on your Mac.

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How to Install two MacOS Versions on One Computer

Step 1. How to get a beta version of MacOS for developers

You can join the Apple developer program and get your beta MacOS absolutely for free. To do it, you need to register as a developer at the official Apple website, and it can be done without subscription.

Go to the official Apple website and click – Enroll.

And the button below – Start Your Enrollment.

Then enter your Apple ID and you’ll be suggested to download an app and continue your registration from there, or do it from the browser.

Download the app – Apple Developer.

Open Account and type your Apple ID to sign in.

After that, click on Enroll Now to register in the Apple Developer Program.

Then click Continue and I agree.

After your enrolment is complete, the system settings will display an option to enable beta updates. Open System Settings – General – Software Updates – Beta Updates.

Choose the beta version of the required operating system from the drop-down list.

After that, the operating system will check for updates. As a result, the selected MacOS beta version should be displayed here.

To download it and update your system, click Upgrade Now. When the process is over, you will get a new version of your operating system.

With this method, you’ll be able to get the latest beta version of your MacOS and start testing it.

Step 2. How to partition your hard disk

To install two MacOS versions on one computer, you need to know how much free space is available on your hard disk, and if this space is enough to install another operating system. For MacOS Sonoma, you need at least 14 Gb of free disk space. If you don’t have that much space, clean up your disk.

When you’re done with that, you need to divide the main volume on your hard disk into several parts using the disk utility. To do it, open Launchpad – Other – Disk Utility. In the app window, click on View and choose Show All Devices. This will allow you to see the volumes on your hard disk.

Here, you should have a volume called Macintosh HD or Home. Select it and click on the plus button to create a new volume.

Set a name for this new volume and click Add.

If necessary, you can change the settings and set a size limit for this new volume.

As a result, you get a new volume. Now, you can use it to install one more version of the operating system.

Step 3. How to install two versions of MacOS on one Mac

Now that you have divided the hard disk into two volumes, you can start installing the second MacOS. For starters, you should download an installer for the required MacOS version.

Open Appstore, find and download the required installer.

There is no beta version in App Store, but you can download it later, using the method that involves Apple Developer app. With App Store, you can only download the available versions. If you’re looking for an older version, this process will be more complicated. Such installation will have to be done from the Recovery menu and with a bootable drive.

A bit later, you’ll see how to add a second operating system, but for now we’ll continue with the more traditional method.

When the download is complete, run the installer.

Now choose the volume where to install MacOS, and click Continue.

Type your administrator password, and the installation will begin. Wait until the process is complete.

When it happens, your Mac will reboot, and this time it will boot from the new volume where you have installed the new operating system. This is followed by a typical sequence of configuration steps.

As you sign in to your computer, you’ll be able to update this MacOS version to a new beta version using the method we have explored a few minutes earlier: download Apple Developer, sign in with Apple ID to register as a developer. After that, go to System Settings to enable beta updates, download and install a new beta version of MacOS.

As a result, your Mac will reboot and the installation will begin. In the end, your Mac will have two MacOS versions, the main one and the beta one. Your Mac will boot from the new volume, that is, from the latest operating system you have installed.

To boot the main operating system, restart your Mac while holding down the Options key. Choose the main volume to boot from.

Then the main operating system will boot.

You can also configure the disk to boot from in the System Settings. To do it, open System Settings – General – Startup Disk.

Select the necessary volume and click the Restart button to reboot. As a result, your Mac will boot from the selected volume.

Additional method. How to install two MacOS versions on one computer with the Recovery menu

One more method to install the second MacOS version on the same computer is by using the Recovery menu.

Boot your Mac in the Recovery Mode by holding down the Cmnd + R keys, and starting up the computer. Hold down the keys until the Apple logo appears on your screen.

Run Disk Utility from the Recovery menu and create a new volume.

Then get back to the main menu and choose Reinstall MacOS from the list.

Select the new volume for installation.

As a result, your computer will receive two versions of MacOS.

Conclusion

Summing up, now you have two versions of MacOS on one computer, and you can easily switch between them by just rebooting your Mac and choosing the one you need. This gives users an opportunity to test new operating system features and try out various third-party apps while preserving the stable working environment of the main operating system. This is how you ensure safe operation of your Mac at all times.