I found an issue that reproduces on your demos too:
1. Open the editor, goto HTML mode.
2. Paste the following HTML in the editor:
3. Goto Design mode, click anywhere in the text and press ENTER.
4. Goto to HTML mode and count the BRs and delete them.
5. Repeat steps 3 and 4 and observe how the number of BRs increases by 1 with each cycle.
Please note that this issue doesn't reproduce if the initial content doesn't contain the HTML, HEAD and BODY.
1. Open the editor, goto HTML mode.
2. Paste the following HTML in the editor:
<
html
>
<
head
>
<
title
>A page</
title
>
</
head
>
<
body
>
Some text content in the BODY. Press ENTER with the cursor placed anywhere in this text. Go to HTML mode, count how many BRs were created and delete the BRs. Go back to design mode. Press ENTER again, go back into HTML mode and count the BRs again. Repeat. You'll notice that a BR is added after each cycle. This happens only when the HTML and BODY tags are present in the HTML code; doesn;t happen when only the text is pasted in the editor in HTML mode.
</
body
>
</
html
>
4. Goto to HTML mode and count the BRs and delete them.
5. Repeat steps 3 and 4 and observe how the number of BRs increases by 1 with each cycle.
Please note that this issue doesn't reproduce if the initial content doesn't contain the HTML, HEAD and BODY.