Data merging and cleaning

I have x2 databases from software exports that I need to be cleaned, de-duped and correlated to create a clean excel file to upload into Salesforce.

There are two databases, one (sheet 1) with 5,60 rows of data. These need to be checked and de-duped where the entry may have been created twice due to a typo for example.

The second (sheet 2) has 2,332 rows where I need to check the account code from sheet 1 matches the code on sheet 2. Where sheet 2 has a different account code, sheet 1 must be updated.

Finally prepare. the data on sheet 1 for upload to SalesForce using a new template provided.