Excel 2010 :: VLookup Between 2 Workbooks Taking Into Account Duplicates On Source?

I've got 3 columns of formulas that end up doing what I need, but I'm thinking it could probably be done easier with VBA.

I have 1 book with a sheet I'll call Log & another book with a sheet I'll call Source. On the Log, column E has the first 9 characters of vendor names & /vendor number (ex: EDMUND FI/00250), along with other data out through column P. On Source, the vendor names are in C & a short code for their name is in A.

I need to compare the first 9 characters in Log col E with the first 9 characters in Source col C. When a match is found, I need to return the short code from Source col A. BUT - if there's a duplicate in either Source col C or A, instead I need to return the word VERIFY, preferably with the cell highlighted in red.

Right now, I have, on Source col L:

Code:
=MID(C2,1,9)
and in source M:

Code:
=IF(OR(A2=A1,A2=A3,L2=L1,L2=L3),"VERIFY",A2)
This gives me the first 9 characters of the vendor name in L & the short code OR VERIFY in M

Then, in Log col R, I have an array formula:

Code:
=VLOOKUP(MID(E4,1,9),'[PRETICKET P ADDRESSES working.xls]Paddress'!$L:$M,2,FALSE)

This gives me either the short code or VERIFY from Source M. Also, sometimes it doesn't find a match & it returns #N/A. Then I have to do Conditional Formatting to make the VERIFY cells red & I thought I'd make the error cells be yellow (although I haven't figured out the CF for that yet)

Is there a better way to do this with VBA? I'm working with Excel 2010; just got it & still figuring it out.