One might think they were trying to be clever by introducing little discrepancies, bur rather over-egged the pudding in doing so..
Or.....the story they told had no basis in reality at all;
"I read carefully the written document/questionnaire provided by David Payne."
but was not able to extricate any other information besides what is already known. He declares that he saw Madeleine, for the last time, at 17H00 on 3/5/07 in the McCann apartment. Also present there were Kate and Gerry. He did not indicate the motive for being there or what he was doing. He also cannot indicate how long he stayed.
I examined once again the declarations of Fiona Payne. In her depositions, she states that she went to the McCann apartment, around 19H00, on the 3rd of May, together with Kate. She states afterwards that, 10 minutes later, the husband arrived; it is not clear which husband she refers to.
http://www.mccannpjfiles.co.uk/PJ/Gaspar.htm