In Developer, Computed (style) has entry that does not correctly represent sub-entries

[pydemon]

Description

As title says - when in the developer, inspecting an element, computed (style) tab:
found an entry (float) that showed "none", when the 2 sub entries both showed "left" -
unless I am mistaken, the final result should reflect the highest priority CSS selector

Steps to Reproduce

1. go to url: https://devblogs.microsoft.com/scripting/weekend-scripter-manage-window-placement-by-using-pinvoke/
2. Inspect (right-click): Nav menu / Microsoft logo-link (top left pic on page)
3. Developer, styles tab: <a id="uhfLogo" ...> tag logo - NOTE: the webpage has a
   duplicate CSS file entry, so affected tags (like this one) will show 2 duplicate entries,
   1 for each CSS reference.
4. Computed (styles) tab: float: none, but both (duplicated) sub-entries show "left", and the element behaves as a left float (as expected)

Actual result:

Computed (styles) tab has element float property of: float: none
screen shot:

Note: developer overlays webpage, with logo-link selected on webpage, and computed tab showing "float: none", where both sub-entries show "float:left"

Expected result:

Computed (styles) tab should have element float property of: float: left

Reproduces how often:

Every time in this specific case, including in a few previous versions.

Brave version (brave://version info)

Brave 0.68.142 Chromium: 77.0.3865.90 (Official Build) (64-bit)
Revision 58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS Windows 10 OS Version 1903 (Build 18362.356)
JavaScript V8 7.7.299.11
Flash (Disabled)
User Agent Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.90 Safari/537.36
Command Line "C:\Program Files (x86)\BraveSoftware\Brave-Browser\Application\brave.exe" --incognito --enable-dom-distiller --disable-domain-reliability --disable-chrome-google-url-tracking-client --no-pings --extensions-install-verification=enforce_strict --enable-features=NewExtensionUpdaterService,WebUIDarkMode,SimplifyHttpsIndicator --disable-features=AudioServiceOutOfProcess,AutofillServerCommunication,LookalikeUrlNavigationSuggestionsUI,UnifiedConsent,TranslateUI --flag-switches-begin --load-media-router-component-extension=1 --enable-features=NewExtensionUpdaterService,WebUIDarkMode,SimplifyHttpsIndicator,CastAllowAllIPs --disable-features=AudioServiceOutOfProcess,AutofillServerCommunication,LookalikeUrlNavigationSuggestionsUI,UnifiedConsent,TranslateUI,NewEncodeCpuLoadEstimator --flag-switches-end
Executable Path C:\Program Files (x86)\BraveSoftware\Brave-Browser\Application\brave.exe
Profile Path C:\Users\Rodney\AppData\Local\BraveSoftware\Brave-Browser\User Data\Default

Version/Channel Information:

I'm new to brave, and am not brave enough to try the less stable versions.

• Can you reproduce this issue with the current release? Yes, also saw this
  in Release Channel v0.67.125, 131, 139, besides current active (non pre-release) 142
• Can you reproduce this issue with the beta channel? - not tried
• Can you reproduce this issue with the dev channel? - not tried
• Can you reproduce this issue with the nightly channel? - not tried

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
  No - issue still present
• Does the issue resolve itself when disabling Brave Rewards?
  Not checked - just starting brave - have not researched/enabled rewards
• Is the issue reproducible on the latest version of Chrome? I avoid chrome like the plague.
  Google is evil. Have a friend that works at google. You couldn't pay me to use it.
  Still struggling to replace gmail...

Miscellaneous Information:

I have installed 2 powerful extensions not "validated" by brave - not likely to impact developer, but just in case:

1. ublock Origin,
2. uMatrix
   yes I know they recommend removing Origin if using uMatrix,
   but Origin blocks stuff matrix can't, and matrix has much better granular control,
   and I have had no problems using them together)

There are also 4 other extesions, but they don't muck around with the inner-workings of Brave,
so are probably not worth worrying about, but just-in-case, they are:
Context Menu Search 2.93, Copy All Urls 2.10, Fakespot 0.6.4, and LastPass 4.33.5

P.S. - keep up the great work!