Double Invoice booking(Receipt Matching) is allowing for Purchase order in payable module

HI Friends

We have created one purchase Order with 3 Way Receipt Matching for 10 qty and Purchase receipt booked for 10 qty.

In Payables Module one user booked Invoice on 29-jul-2012 and another user for the same receipt on 14-aug2012.

we have given Invoice tolerance as Zero at purchase order level Still double invoice got booked and double payment happend

 i cross check with other Purchase orders also where already goods receipt  it is allowing the user for the same receipt to book the invoice it results to double payment

Note: For easy understanding i attaching screenshots

Ravi.G