Can I compare 2 lists to combine duplicate entries in new list?
 

I am trying to take a very long list of customers, and compare it to current
"live" customers, and create a single database (one from Excel, one from
Goldmine which I've imported into an Excel worksheet). I want to take the one
list of Live, and expand it to include some data that is only in Goldmine, so
I'm creating a third sheet that has the information from Goldmine, but limit
it to only the "live" customers.
So far, I've only been able to match exact cells Match('sheet 1'A3, 'Sheet
2', A3), which indicates a match in like cells in two worksheets. I want to
take a list of over 2000 and a list of 120, and have an output of 120, with
combined information with the Goldmine (2000+ list) columns matching up with
the "live" customers, thus creating a new list. The columns shouldn't matter,
as long as I can find matching lists from a column in one sheet with a column
in the other sheet.
Thanks in advance for any ideas.