to reproduce please build jdk then go to awt docs folder and run tidy against Color.html:

$ tidy -e src/build/linux-x86_64-normal-server-release/docs/api/java/awt/Color.html

line 699 column 1 - Warning: <a> anchor "WHITE" already defined
line 747 column 1 - Warning: <a> anchor "GRAY" already defined
line 795 column 1 - Warning: <a> anchor "BLACK" already defined
line 819 column 1 - Warning: <a> anchor "RED" already defined
line 843 column 1 - Warning: <a> anchor "PINK" already defined
line 867 column 1 - Warning: <a> anchor "ORANGE" already defined
line 891 column 1 - Warning: <a> anchor "YELLOW" already defined
line 915 column 1 - Warning: <a> anchor "GREEN" already defined
line 939 column 1 - Warning: <a> anchor "MAGENTA" already defined
line 963 column 1 - Warning: <a> anchor "CYAN" already defined
line 987 column 1 - Warning: <a> anchor "BLUE" already defined
line 1996 column 183 - Warning: <a> attribute "href" lacks value
line 192 column 2 - Warning: trimming empty <p>
Info: Doctype given is "-//W3C//DTD HTML 4.01 Transitional//EN"
Info: Document content looks like HTML 4.01 Transitional
13 warnings, 0 errors were found!

In the body of Color.html there are, e.g., two similar anchors for white (name is case insensitive):

  <a name="white">
  <!-- -->
  </a>
  
  <a name="WHITE">
  <!-- -->
  </a>
  
I guess they respond to the following lines in source file (Color.java):

    public final static Color white = new Color(255, 255, 255);
    public final static Color WHITE = white;

So the navigation is disturbed.

Can see that for some other generated docs.