Try something like this...

Data Range
A
B
C
D
E
1
WO#
Auction
------
Auction
WO#
2
WO1
28
39
WO2
3
WO2
39
WO4
4
WO3
20
WO5
5
WO4
39
WO10
6
WO5
39
7
WO6
25
8
WO7
17
9
WO8
12
10
WO9
30
11
WO10
39


This array formula** entered in E2:

=IFERROR(INDEX(A:A,SMALL(IF(B$2:B$11=D$2,ROW(B$2:B$11)),ROWS(E$2:E2))),"")

** array formulas need to be entered using the key
combination of CTRL,SHIFT,ENTER (not just ENTER).
Hold down both the CTRL key and the SHIFT key
then hit ENTER.

Copy down until you get blanks.