shows multiple versions of Microsoft Office ( 2021 & M365) and using same key code.

Question

Why The list of installed applications shows multiple versions of Microsoft Office ( 2021 & M365) and using same key code. now only install M365, but it was removed 2021 by tool

Answer 1

Dear @Chiu, Daniel W H,

Thank you for posting your question in the Microsoft Q&A forum.

Based on your description, even though the system is only running Microsoft 365 Apps, Microsoft Office LTSC 2021 is still displayed in the Windows Apps / Programs and Features list.

The fact that the device displays both Microsoft Office 2021 and Microsoft 365 Apps in the app list does not necessarily mean that both versions are running simultaneously.

To verify that the Office version you're using is actually working.

You can open any Office application (Word/Excel/Outlook) > File > Account:

If Microsoft 365 Apps is displayed and the login account is a subscription account, then only Microsoft 365 Apps is being used.

If you want to completely clean your system so that the Apps/Programs and Features list only displays Microsoft 365 Apps. Here is suggestion you can refer to:

Completely uninstall Office using Microsoft Support and Recovery Assistant (SaRA)

Download the SaRA tool from the official Microsoft link:

Uninstall Microsoft 365 or Office from a PC

Run the SetupProd_OffScrub.exe file

Select the version of Office you want to uninstall (e.g., Office 2021 or select All to uninstall completely)

Follow the on-screen instructions

Restart your computer when prompted

For reference Scenario: Office Uninstall

I hope information above meet your expectations, if it does not, please leave the comment below so I can support you more effectively.

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Answer 2

This is mainly issue , now it is actually only M365 can be running , but it is still show 2021 office installed in App installation of window.

Answer 3

The list of installed applications can show both “Office 2021” and “Microsoft 365” even though only Microsoft 365 is currently installed because of how Office versions and installation technologies are handled, and because old entries or license information can remain after removal.

Key points that explain the behavior:

1. Multiple versions previously on the same PC

• Office 2021 and Microsoft 365 share the same internal version number (16.0), so tools and lists can show them in a confusing way.
• When more than one version or edition is (or was) installed on the same computer, side‑by‑side support is limited:
  • In most cases, subscription Microsoft 365 and non‑subscription Office 2021/2019/2016 cannot run together on the same computer.
  • An exception exists only when one product is MSI (volume license) and the other is Click‑to‑Run, and even then there are strict compatibility rules.
• If Office 2021 was installed first and then Microsoft 365 was added, this can create conflicts or duplicate-looking entries until the older version is fully removed.

2. Why Office 2021 was removed by the tool

• Microsoft explicitly does not support certain combinations, such as:
  • Multiple Office versions with Remote Desktop Services enabled.
  • The same version of Office installed both as Click‑to‑Run and MSI.
  • Some mixed Click‑to‑Run scenarios with overlapping apps.
• To move to a supported state, the official uninstall/removal tool removes the incompatible or older Office installation (for example, Office 2021) so that only Microsoft 365 remains. This is expected behavior when resolving version conflicts.

3. Why it looks like both versions use the same key code

• Newer Office versions (Office 2024, 2021, 2019, and Microsoft 365) are usually activated by signing in with the associated Microsoft account, not by a unique product key per device.
• Many key‑viewing tools show a generic or shared key fragment for these account‑based installations, so it can appear that Office 2021 and Microsoft 365 “use the same key,” even though activation is actually tied to the account/license, not that visible code.
• If multiple one‑time‑purchase Office products were bought and installed using the same Install button, activation can fail on other PCs and requires changing the product key on those PCs. This is a licensing/activation behavior and does not mean that Microsoft 365 and Office 2021 truly share a single retail key on one machine.

4. Current situation: only Microsoft 365 installed

• After running the removal tool, Office 2021 is uninstalled so that only Microsoft 365 remains, which matches supported guidance for avoiding version conflicts.
• If any “Office 2021” entry still appears in inventory or tools, it is typically a leftover registry or cache entry rather than an active installation.
• The supported and recommended configuration is to keep only one active Office product set (for example, Microsoft 365 Apps) on the device.

In short, the list showed both Office 2021 and Microsoft 365 because they were previously installed together, and activation/account information can make them appear to share the same key. The removal tool correctly removed Office 2021 so that only Microsoft 365 remains in a supported configuration; any apparent shared key is just how modern, account‑based activation is represented.

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References:

• Install and use different versions of Office on the same PC
• Supported scenarios for installing different versions of Office, Project, and Visio on the same computer
• Office installed with Click-to-Run and Windows Installer on same computer isn't supported
• Change your Office product key