Here are some conflicting results when comparing date objects to strings using ColdFusion

CFML_date_comparison.cfm

<!--- 20201210 Comparing dates with ColdFusion
GIST: https://gist.github.com/JamoCA/7fc7e05ff7121cb481989b57c05c3bd5
--->

<h1>CFML Date Comparison</h1>
<ul>
  <li><b>TRYCF:</b><ul>
    <li>TRUE when using ColdFusion 2016 or Lucee 5, Lucee 4.5 or Railo 4.2.</li>
    <li>FALSE when using ColdFusion 10, 11, 2018 & 2020. (NOTE: CF10 doesn't support ISO dates.)</li>
  </ul></li>
  <li><b>CFFiddle:</b><ul>
    <li>TRUE when using ColdFusion 2016 or 2020.</li>
    <li>FALSE when using ColdFusion 2018.</li>
  </ul></li>
</ul>

<cfoutput>
  <h2>"1/2/1999" IS parseDateTime("January 2, 1999")</h2>
  #YesNoFormat("1/2/1999" IS parseDateTime("January 2, 1999"))#

  <h2>"1/2/1999" IS parseDateTime("1999-01-02T00:00:00")</h2>
  #YesNoFormat("1/2/1999" IS parseDateTime("1999-01-02T00:00:00"))#
</cfoutput>