Hello Adam,
when pasting a text in HTML mode with CTRL-V the text appears always twice.
2) Switch to HTML-Mode
3) Paste a text with CTRL-V without selecting a text area before. You will see that the text appears twice.
I also found out, if you select a text area before and then paste a HTML code like <div><div><div><div>
with CTRL-V then the code will not appear. Probably the code gets filtered.
Joerg