Removing duplicate records in a different way..

Hello & thanks for viewing...
I am very much a beginner Excel user. I hope I explain this accurately. Please bear with me.
I have a spreadsheet with 232,000 records.. in each row is.. Fname, Lname, street address, city,st,zip
I then took those 232,000 and outsourced an append job.. where I had additional fields appended in a separate process
to SOME of the 232,000. What I got back from my vendor was a separate Spreadsheet that had 50,000 records with appended info added to each row.

Problem is.. now I have a second spreadsheet with 50,000 that I need to put back into the 232,000 of course the 50,000 will be duplicates to 50,000 in the main 232,000. I want to drop my new 50,000 back into my 232,000 and remove those original 50,000 which are now dupes.

I probably took the LONG way to explain this, but I wanted to be clear.

any suggestions..? much appreciated in advance..

John