I will go ahead and inject my opinion on this since I've had this come up a lot before. This may have already been answered satisfactory but I thought I'd chip in. If the reimbursements are included on the 1099 and the expenses are accountable to the payor from the payee/contractor, then these are 100% deductible as "reimbursed expenses". If for example the expense reimbursed includes meals those meals are part of the reimbursed expenses and 100% deductible and not reduced by the otherwise 50% reduction. The payor would be responsible for the 50% reduction for meals paid.
Hope this helps.
