Copy and paste content in editor results in indented text and undesirable markup being entered

Steps to reproduce:

1. create a new page, enter two paragraphs of text, e.g:

   <p>foo</p>
   <p>bar</p>
   

2. now select both these paragraphs using Ctrl + A or Cmd + A
3. copy and then paste back into the same editor
4. this will result in this markup:

   <p>foo</p>
   <p>bar</p>
   <div style="margin-left: 10px;" data-mce-style="margin-left: 10px;">
       <p>foo</p>
       <p>bar</p>
   </div>
   

Reproducible in Chrome 14 and 15.