Match OR Iferror formula

Hi there

Please assist with the following:

What I want to achieve is to identify the duplication between both tabs, but highlight the duplicate in "unmatched" tab

For example, as per attached.

Company Tab:
PROPERTY ACCOUNT
11523 020486
16681 020486
16686 020486

See the Account number appears 3 times, but there 3 property attached to that specific account number. So we need to use the Account number (1st part of the search) and Property number (2nd part of the search).

Do you get it??
I want to ensure that these records in "Company" tab doesn't duplicate in "unmatched" tab, highlight this cases so i can remove them from the table.

Again...
I would like to highlight them in the "unmatched" tab

"company" tab
PROPERTY ACCOUNT
11523 020486
16681 020486
16686 020486

"unmatched" tab
PROPERTY ACCOUNT
11523 020486
16681 020486
16686 020486

I have gotten a solution for windows, i replace the ',' with ';" but still doesn't seem to work on mac platform
=IFERROR(IF(MATCH(A2&B2,Company!$A$2:$A$2500&Company!$B$2:$B$2500,0),1,""),"")

Please help

Thank you