For performance reasons we use our own NUnit test runner, export an XML file with test results and upload that to https://ci.appveyor.com/api/testresults/nunit/jobid. Recently apparently the parser for those files have changed which now leads to tests appearing multiple times. Now apparently every test-case below every test-suite is counted once for each test-suite. Given the following test file I reduced to just three test cases in five nested test suites:

<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!--This file represents the results of running a test suite-->
<test-results name="D:\Users\Joey\VCS\Pash\Pash.nunit" total="1657" errors="0" failures="0" not-run="28" inconclusive="0" ignored="20" skipped="8" invalid="0" date="2014-09-08" time="22:31:47">
  <environment nunit-version="2.6.1.12217" clr-version="2.0.50727.8000" os-version="Microsoft Windows NT 6.2.9200.0" platform="Win32NT" cwd="D:\Users\Joey\VCS\Pash" machine-name="JESSICA" user="Joey" user-domain="JESSICA" />
  <culture-info current-culture="de-DE" current-uiculture="en-GB" />
  <test-suite type="Project" name="D:\Users\Joey\VCS\Pash\Pash.nunit" executed="True" result="Success" success="True" time="32.681" asserts="0">
    <results>
      <test-suite type="Assembly" name="D:\Users\Joey\VCS\Pash\Source/TestHost/bin/Debug/TestHost.exe" executed="True" result="Success" success="True" time="15.409" asserts="0">
        <results>
          <test-suite type="Namespace" name="TestHost" executed="True" result="Success" success="True" time="15.409" asserts="0">
            <results>
              <test-suite type="TestFixture" name="ArraySubexpressionOperator" executed="True" result="Success" success="True" time="1.909" asserts="0">
                <results>
                  <test-suite type="ParameterizedTest" name="Onedimensional" executed="True" result="Success" success="True" time="1.740" asserts="0">
                    <results>
                      <test-case name="TestHost.ArraySubexpressionOperator.Onedimensional(&quot;@($a)\t\t \t\t\t\t# result is the same array of 3&quot;)" executed="True" result="Success" success="True" time="1.675" asserts="1" />
                      <test-case name="TestHost.ArraySubexpressionOperator.Onedimensional(&quot;@(@($a)) \t\t\t\t# result is the same array of 3&quot;)" executed="True" result="Success" success="True" time="0.029" asserts="1" />
                      <test-case name="TestHost.ArraySubexpressionOperator.Onedimensional(&quot;$a&quot;)" executed="True" result="Success" success="True" time="0.019" asserts="1" />
                    </results>
                  </test-suite>
                </results>
              </test-suite>
            </results>
          </test-suite>
        </results>
      </test-suite>
    </results>
  </test-suite>
</test-results>

I get a total of 15 test results in the web interface (https://ci.appveyor.com/project/ygra/pash/build/1.0.59/tests). My guess would be that the change was to enumerate all descendatn test-case elements below every test-suite instead of just direct children (perhaps an XPath expression that was changed to something too greedy here).