The copied text is pasted multiple times after switching back from Source

Follow this steps to reproduce:

• create a new page and save
• edit it in-place
• type some text and copy some part of it
• paste below the typed text <- the text is pasted once
• switch to Source, remove the pasted text and switch back to WYSIWYG mode
• paste again below the typed text <- the text is pasted twice
• switch to Source, remove the pasted text and switch back to WYSIWYG mode
• paste again below the typed text <- the text is pasted 3 times

It seems like each time we get back from Source a new paste listener is added and thus the text is pasted multiple times, by each of the added listeners.