Can I be long and short the same underlying contract simultaneously?

Overview: 

IB does not offer this particular account structure.  While IB does offer stock and option trading in the same account as futures/commodities trading, there is no account structure here where traders can be short and long the same underlying contract simultaneously.

Background: 

This could occur if an account holder had more than one account.  For example, this account holder could short an XYZ June 2009 45 call in account UXXXXX1, and go long the same XYZ June 2009 45 call in account UXXXXX2.  However, if the account is short 1 XYZ June 2009 45 call in account UXXXXX1, and buys one June 2009 45 call in account UXXXXX1, this would close the short position.