I have 2 columns of data, several thousand rows and growing. Column B has
120 unique entries. Column C has 500 unique entries. I am using the
following array formula (very successfully thanks to Biff) to pull out the
unique entries from Column C.

{=IF(ROWS($1:1)<=SUM(1/COUNTIF(A$2:A$20,A$2:A$20)),INDEX(A$2:A$20,SMALL(I F(ROW(A$2:A$20)-MIN(ROW(A$2:A$20))+1=MATCH(A$2:A$20,A$2:A$20,0),RO W(A$2:A$20)-MIN(ROW(A$2:A$20))+1),ROWS($1:1))),"")}

Now i would like to pull the unique entries from Column C that are unique to
only each unique entry in Column B.

For example:

Col A Col B
ABC 123XYZ
DEF 123XYZ
ABC 456LMN
GHJ 123XYZ
ABC 789STV

I want to list in Cols E and F:

Col E Col F
ABC 123XYZ
ABC 456LMN
ABC 789STV

Thanks,
casey