Draft email copied content from one and sent in other

I have an employee here who had 2 drafts, both were replys to different emails with different subjects and different recipients. After completing one of the emails, they pressed send and that was that.

After getting back to the office, they noticed in their sent items that the sent email contained the full text of the other item in drafts below the content of the intended email. It was formatted as so:

<the intended email content was here>

On Jan 4, 2013, at 2:05 PM, "John Smith" <jsmith@foo.com> wrote:

Hi Bob,

Blah blah blah... <long email with many replys>

Everything from "On Jan 4, 2013, at 2:05 PM..." and onward was from the other draft.

Is this a known issue? Anyone ever run into this before?

This was with an Exchange email account on iPhone 5 at 6.0.2.