年月指定 取不重複 (14975)

D2:F4{=IFERROR(SMALL(IF((COUNTIF($C2:C2,$H$2:$H$8)=0)*(DATE($A2,$B2,1)=EOMONTH(N(IF({1},$H$2:$H$8)),-1)+1),$H$2:$H$8),1),"")

另解{=IFERROR(SMALL(IF((COUNTIF($C2:C2,$H$2:$H$8)=0)*($A2&"-"&$B2=TEXT($H$2:$H$8,"YYY-M")),$H$2:$H$8),1),"")