Randomly allocate members to groups in Excel

[GinaS]

I have a list of 34 names which I need to randomly assign to one of 8 teams. This will run on a monthly basis and as such, I need each month for a new team to be generated and no person repeated in a group they have been in the previous months (see below). I have been using the formula =VLOOKUP(RANDBETWEEN(1,8),$B$33:$C$40,2,FALSE) to generate the random allocation but don't know how to make it not repeat the following month.

Any help would be GREATLY appreciated! Thanks!

		Team allocation
Ref	Name	Nov-13	Dec-13	Jan-13	Feb-13	Mar-13	Apr-13	May-13	Jun-13
1	Tracy	Purple	Purple	Pink	Red	Black	Grey	Orange	Purple
2	Peter	Purple	Blue	Blue	Orange	Purple	Pink	Pink	Blue
3	Jane	Blue	Grey	Red	Black	Blue	Pink	Grey	Grey
4	Natalie	Purple	White	Black	Orange	Black	Grey	Black	Orange
5	Barry	Black	Grey	Orange	Pink	White	Orange	Pink	Black
6	Chris	Grey	Red	Blue	Red	Purple	Orange	Blue	Purple
7	Andrew	Blue	Orange	Pink	Black	Purple	Blue	White	White
8	Alex	Orange	Purple	Grey	Purple	Orange	Grey	Black	Blue
9	Leo	Blue	Purple	Black	Blue	Pink	Grey	Black	White
10	Lisa	Red	White	Pink	Pink	Orange	Pink	Orange	Grey
11	David	Red	Red	Pink	White	Blue	Purple	Blue	Blue
12	Dave	Black	Grey	Grey	Blue	Orange	Red	Pink	Grey
13	Loius	White	Purple	White	White	Pink	Pink	Orange	White
14	Claudia	Pink	Blue	Blue	Blue	White	Red	Red	Blue
15	Kim	Blue	Red	Pink	Purple	Red	Orange	Red	Pink
16	Chad	Grey	Blue	Red	Orange	Grey	Pink	Red	Grey
17	Robbie	Black	Blue	Orange	Black	Blue	Blue	Grey	Black
18	Tim	Black	Red	Black	White	Red	Pink	White	White
19	Don	Purple	Red	Black	Red	White	Pink	Grey	Orange
20	James	Grey	White	Pink	Pink	White	Orange	Black	White
21	Sam	Purple	Blue	Orange	Orange	Grey	Grey	Purple	Pink
22	Stacey	Pink	Grey	Red	Purple	Grey	Grey	Blue	Black
23	Candice	Orange	Red	Red	Red	Black	Grey	White	Purple
24	Lauren	Grey	Purple	White	Pink	Pink	Red	Red	Pink
25	Paul	Red	Black	White	White	Red	Pink	Black	Purple
26	Tom	Grey	Black	Blue	Red	Purple	Red	Orange	Red

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