thanks for the reply.

the reason, there are 2 entries for Pulse for each user, because first
user can work on this vendor but even though the second user has been
assigned with the same supplier, he cannot work with this vendor, but
it will be worked by the team leads. these vendors are called as
problem vendors.

what i used to initially was to do a vlookup for the vendor name in
the main sheet with the another sheet which contains the list of the
problem vendor.

Main sheet
User                     Vendor Name
Kueyson Yee     LIEBHERR AEROSPACE TOULOUSE SA
Kueyson Yee     PULSE MIL AEROSPACE DIV
Kueyson Yee     PULSE MIL AEROSPACE DIV
Lisa Thompson   LIEBHERR AEROSPACE TOULOUSE SA
Lisa Thompson   PULSE MIL AEROSPACE DIV
Lisa Thompson   PULSE MIL AEROSPACE DIV

Lookup Sheet:
User                         Vendor
Kueyson Yee     PULSE MIL AEROSPACE DIV
Lisa Thompson   LIEBHERR AEROSPACE TOULOUSE SA

so what i want is to check for the user name in the Lookup sheet and
then, identify the vendor he cannot work with. from the above example:

in the main sheet, i have to identify out of 2 vendors, Pulse and
LIEBHERR, on which vendor user Kueyson Yee cannot work with. if the
user can work, then cell value should be "Yes" else it should be
"No".

Hope i am clear with my problem. thanks again for helping.