It would not be the first time that the ban was "bent." There are numerous examples of Islamic art depicting human and animal figures - I found a couple here:
http://www.lacma.org/islamic_art/lia.htm.
Was this a total ban on depicting the human form, or was it specific in some way? I remember seeing painting that contained the figure of the Prophet Mohammed, but with his face completely hidden by a veil, which I think was how the ban was complied with in that case. How strictly it was enforced might have just depended on who was in charge at the time.