取四位并保留唯一值 (11103)

C2{=IFERROR(RIGHT(SMALL(IF(COUNTIF(C$1:C1,MID(B$2:B$16,5,4))=0,ROW($2:$16)/1%%+MID(B$2:B$16,5,4)),1),4),"")

另解 D2=MID(OFFSET(B$1,MIN(IF(COUNTIF(D$1:D1,MID(B$2:B$16,5,4))=0,ROW($1:$15))),),5,4)