If you are responding to or creating a new ticket, you cannot copy and paste any content from a website or email without the "Description" field duplicating itself. For example if I copy a link from my outlook email and paste it in the description field on freshdesk, a new description field appears below the original one. I assume it is doing this because it doesn't like the hidden characters being copied over, since I can copy and paste fine from notepad which strips hidden html entities.
I've attached a screenshot. Using Firefox 19.0.2.