<p dir="auto">In my application, I update figures every several seconds. I am not sure why, but WebAgg backend tends to draw text wrong. For example:</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://camo.githubusercontent.com/97dcb8bc0587aaa54af2ea37c413be9dfa002b891f11c2702917abc96c9c97cf/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f323739333535312f323231373331352f38376231303333652d396131612d313165332d396137342d3964373664616431343337662e706e67"><img src="https://camo.githubusercontent.com/97dcb8bc0587aaa54af2ea37c413be9dfa002b891f11c2702917abc96c9c97cf/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f323739333535312f323231373331352f38376231303333652d396131612d313165332d396137342d3964373664616431343337662e706e67" alt="webagg_text" data-canonical-src="https://f.cloud.github.com/assets/2793551/2217315/87b1033e-9a1a-11e3-9a74-9d76dad1437f.png" style="max-width: 100%;"></a></p>
<p dir="auto">The bottom-left matrix should contain the same labels as the upper-right. Sometimes, even the upper-right matrix is displayed without text, but after some time it recovers. Sometimes, the text for the bottom-left matrix is drawn on the upper-right matrix, causing unreadable overlapped labels.</p>
<p dir="auto">I wonder, where I should start digging for that difference between drawing boxes and color (always valid) and text (randomly skipped on some figures)?</p>
<h3 dir="auto">Bug summary</h3>
<p dir="auto">Hi,</p>
<p dir="auto">When using <code class="notranslate">triplot</code> with a <code class="notranslate">label</code> the resulting legend contains two duplicated entries (even though the markers is None):</p>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="
plt.triplot([0,2,1],[0,0,1],[[0,1,2]], label='Label'); 
plt.legend()"><pre class="notranslate"><span class="pl-s1">plt</span>.<span class="pl-en">triplot</span>([<span class="pl-c1">0</span>,<span class="pl-c1">2</span>,<span class="pl-c1">1</span>],[<span class="pl-c1">0</span>,<span class="pl-c1">0</span>,<span class="pl-c1">1</span>],[[<span class="pl-c1">0</span>,<span class="pl-c1">1</span>,<span class="pl-c1">2</span>]], <span class="pl-s1">label</span><span class="pl-c1">=</span><span class="pl-s">'Label'</span>); 
<span class="pl-s1">plt</span>.<span class="pl-en">legend</span>()</pre></div>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/11042162/166437380-3c5a22bd-e404-4224-9907-288f97ff75c5.png"><img width="500" alt="Screenshot 2022-05-03 at 12 17 10" src="https://user-images.githubusercontent.com/11042162/166437380-3c5a22bd-e404-4224-9907-288f97ff75c5.png" style="max-width: 100%;"></a></p>
<p dir="auto">I think expected behavior would be either</p>
<ol dir="auto">
<li>Remove the second legend entry if no markers are given, or</li>
<li>Remove the second legend entry altogether, e.g. by using <code class="notranslate">kw_markers.pop('label',None)</code> around here <div class="Box Box--condensed my-2">
  <div class="Box-header f6">
    <p class="mb-0 text-bold">
      <a href="https://github.com/matplotlib/matplotlib/blob/2aa71eb3559af56c56b9d137790107bffd83cddd/lib/matplotlib/tri/triplot.py#L78">matplotlib/lib/matplotlib/tri/triplot.py</a>
    </p>
    <p class="mb-0 color-fg-muted">
         Line 78
      in
      <a data-pjax="true" class="commit-tease-sha" href="/matplotlib/matplotlib/commit/2aa71eb3559af56c56b9d137790107bffd83cddd">2aa71eb</a>
    </p>
  </div>
  <div itemprop="text" class="Box-body p-0 blob-wrapper blob-wrapper-embedded data">
    <table class="highlight tab-size mb-0 js-file-line-container" data-tab-size="8" data-paste-markdown-skip="">

        <tbody><tr class="border-0">
          <td id="L78" class="blob-num border-0 px-3 py-0 color-bg-default" data-line-number="78"></td>
          <td id="LC78" class="blob-code border-0 px-3 py-0 color-bg-default blob-code-inner js-file-line"> } </td>
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</li>
</ol>
<h3 dir="auto">Code for reproduction</h3>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="see above"><pre class="notranslate"><span class="pl-s1">see</span> <span class="pl-s1">above</span></pre></div>
<h3 dir="auto">Actual outcome</h3>
<p dir="auto">see above</p>
<h3 dir="auto">Expected outcome</h3>
<p dir="auto">see above</p>
<h3 dir="auto">Additional information</h3>
<p dir="auto"><em>No response</em></p>
<h3 dir="auto">Operating system</h3>
<p dir="auto">MacOS</p>
<h3 dir="auto">Matplotlib Version</h3>
<p dir="auto">3.6.0.dev2140+g2aa71eb355.d20220503</p>
<h3 dir="auto">Matplotlib Backend</h3>
<p dir="auto">QtAgg</p>
<h3 dir="auto">Python version</h3>
<p dir="auto"><em>No response</em></p>
<h3 dir="auto">Jupyter version</h3>
<p dir="auto"><em>No response</em></p>
<h3 dir="auto">Installation</h3>
<p dir="auto">pip</p>