Shouldn't be too hard, but as usual I have questions. Why would I cancel when the 1st two are identical? Would I not want to see if my last entry is unique? Your requirement should be based on human interpretation, not computer logic? If I can blindly enter the 3rd field and it passes the test, it is no guarantee that there won't be duplicates. My entry of "receiver" will pass because someone else entered "reciever". Shouldn't you be showing a list of current discrepancy records for a project? That is, project details on top, discrepancies below in a sub form, and if a new one needs to be entered it could be easily determined?
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.