How to set up CKEditor for multiple instances with different heights?

The easiest way to initialize two editors with custom heights is:

$('#editor1').ckeditor({ height: 100 });
$('#editor2').ckeditor({ height: 200 });

or without jQuery:

CKEDITOR.replace('editor1', { height: 100 });
CKEDITOR.replace('editor2', { height: 200 });

AFAIK it isn't possible to change editor's height on the fly.

If these methods weren't working for you, then you were doing sth else wrong.

Update:

Answering to your comment - your question in fact wasn't about CKEditor, but rather about sharing one object with only two different properties. So you can try like this:

var configShared = {
        startupOutlineBlocks:true,
        scayt_autoStartup:true,
        // etc.
    },
    config1 = CKEDITOR.tools.prototypedCopy(configShared),
    config2 = CKEDITOR.tools.prototypedCopy(configShared);
config1.height = 100;
config2.height = 200;

CKEDITOR.replace('editor1', config1);
CKEDITOR.replace('editor2', config2);

CKEDITOR.tools.prototypedCopy is a tool that creates new object with prototype set to the passed one. So they share all properties except of these you override later.

Update 2:

This is the update for the "Update" section in the question :).

There's no quirk in CKEditor's timing or bug or whatsoever - it's pure JavaScript and how BOM/DOM and browsers work plus some practical approach.

First thing - 90% of BOM/DOM is synchronous, but there are a couple of things that aren't. Because of this entire editor has to have asynchronous nature. That's why it provides so many events.

Second thing - in JS object are passed by reference and as we want CKEditor to initialize very quickly we should avoid unnecessary tasks. One of these is copying config object (without good reason). So to save some msecs (and because of async plugins loading too) CKEditor extends passed config object only by setting its prototype to object containing default options.

Summarizing - I know that this may look like a bug, but it's how JS/BOM/DOM libs work. I'm pretty sure that many other libs' async methods are affected by the same issue.

Add this you will get the different toolbar for both CKeditor in single page

<script>

    CKEDITOR.on('instanceCreated', function (event) {
        var editor = event.editor,
            element = editor.element;

        if (element.is('h1', 'h2', 'h3') || element.getAttribute('id') == 'editorTitle') {
            editor.on('configLoaded', function () {
                // Remove unnecessary plugins to make the editor simpler.
                editor.config.removePlugins = 'find,flash,' +
                    'forms,iframe,image,newpage,removeformat,' +
                    'smiley,specialchar,stylescombo,templates';

                // Rearrange the layout of the toolbar.
                editor.config.toolbarGroups = [
                    { name: 'editing', groups: ['basicstyles'] },
                    { name: 'undo' },
                    //{ name: 'clipboard', groups: ['selection', 'clipboard'] },
                  { name: 'styles' },
                    { name: 'colors' },
                    { name: 'tools' }
                  //  { name: 'about' }
                ];
            });
        }
    });

</script>

Update 25 Jun 2019.

Please Use this code to add multiple CKEditor instances with custom height for each one. Easiest way ever.

  <textarea name="editor1" style="height:30px;" class="ckeditor"></textarea>
   <script type="text/javascript">
      CKEDITOR.replace( 'editor1' );
      CKEDITOR.add            
   </script>

<textarea name="editor2" style="height:40px;" class="ckeditor"></textarea>
   <script type="text/javascript">
      CKEDITOR.replace( 'editor2' );
      CKEDITOR.add            
   </script>

<textarea name="editor3" style="height:50px;" class="ckeditor"></textarea>
   <script type="text/javascript">
      CKEDITOR.replace( 'editor3' );
      CKEDITOR.add            
   </script>

<textarea name="editor4" style="height:60px;" class="ckeditor"></textarea>
   <script type="text/javascript">
      CKEDITOR.replace( 'editor4' );
      CKEDITOR.add            
   </script>

<textarea name="editor5" style="height:70px;" class="ckeditor"></textarea>
   <script type="text/javascript">
      CKEDITOR.replace( 'editor5' );
      CKEDITOR.add            
   </script>

Ref: Here

Solution above from Reinmar is working for me, however I decided to give 1 more solution that i used before this one.

It's really simple, all you need to know is that ckeditor create content div element for every instance with almost the same id, only difference is incremental value. So if you have 2,3,4.. instances only difference will be ordinal number. Code is here:

    CKEDITOR.on('instanceReady', function(){
    $('#cke_1_contents').css('height','200px');
}); 

This event will be activated for every instance you have, so if you want to set height for all instances you could create global variable and use it like x in #cke_"+x+"contents, every time event is activated increase x for 1, check which instance in row is with simple if and then set height.

    var x=1;
CKEDITOR.on('instanceReady', function(){
    if(x==1) h='200px';
    else if(x==2)h='400px';
    else if(x==3)h='700px';
    $('#cke_'+x+'_contents').css('height',h);
    x++;
}); 

This is not best solution but it is working, problem is you actually see content div resizing.