Three instances of MRT.exe listed in Norton Insight query

Norton 360, ver. 21.6.0.32:

Norton Insight, in the query "Highest Performance Impact", appears to list multiple instances of some of the files.

The most obvious example is the Malicious Software Removal Tool from Microsoft, mrt.exe.  Yet when I explore my hard drive, I only find one instance, and it is at C:\Windows\System32\mrt.exe.  All three instances listed by Norton Insight have the same location and same modified-date.
Why is it listed three times?
Results from Norton Insight's analysis follow:


Filename: mrt.exe
Full Path: c:\windows\system32\mrt.exe
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Details
Stability Unknown,  Many Users,  New,  Trusted
Origin
Downloaded from
Unknown
Activity
Actions performed: Suspicious actions performed: None
____________________________
Developers
Microsoft Corporation
Version
5.18.10802.0
Identified
11/14/2014 at 7:30:14 AM
Last Used
11/14/2014 at 7:30:14 AM
Startup Item
No
____________________________
Unknown
This program crash history is not known.

Many Users
Millions of users in the Norton Community have used this file.
New
This file was released more than 7 days 11 days ago.
Trusted
Norton has given this file a trusted rating.
____________________________
Source File:
svchost.exe
File Created:
windows-kb890830-x64-v5.18-delta.exe
File Created:
mrtstub.exe
File Created:
mrt.exe
____________________________
Performance
____________________________

Avg. Resource Usage: Heavy
Avg. CPU Usage: Heavy
Avg. Memory Usage: Moderate
____________________________
File Thumbprint - SHA:
bc2b1893e5fc1bbda671ff459218f9f0898e5b5d542696381336656b69017f33
File Thumbprint - MD5:
d92fb5770cbde049a4732b76a77f6864