title: PrivateFontCollection sometimes reporting wrong family name
body: <p>I'm having a strange memory issue. My code works for a while, and then I start getting strange results. I am downloading a font from storage, in byte[], and then trying to add it as a Memory font.</p>
  <pre><code>    PrivateFontCollection pfc = new PrivateFontCollection();
  
  
              var fontData = await _blobManager.Download(fontUrl);
  
              int dataLength = fontData.FileData.Length;
              IntPtr ptrData = Marshal.AllocCoTaskMem(dataLength);
              Marshal.Copy(fontData.FileData, 0, ptrData, dataLength);
  
              pfc.AddMemoryFont(ptrData, dataLength);
  
              Marshal.FreeCoTaskMem(ptrData);
  
              var thisName = pfc.Families[0].Name;
  </code></pre>
  <p>However, this works the first few times, and then I start getting crazy results. Even though I am logging the length of the font collection, which starts at 0 count, as expected... on occasions, and old Font Family name is being reported in the thisFamily variable. Even though I confirm that the font downloaded as the correct family name.</p>
  <p>It seems that maybe the previous sessions has not been cleared and then <code>pfc.AddMemoryFont(ptrData, dataLength);</code> has the old font loaded in that location still. Is this possible? Is there an obvious issue with my code that can cause spurious memory allocation issues?</p>