Hi
Maintain the same assignment value (BSEG-ZUONR) in both the documents. I presume you cannot reverse the MIRO now since it belongs to 2009.
In OB74, maintain the field for clearing for your GR/IR Account only as ZUONR. There after execute, F.13 without GR/IR special tick maintained. Also specify the document no in F.13, which are not getting cleared.
Regards
Sanil Bhandari