sum multiple sheets and delete duplicate rows

Hi to everyone out there. I am new in this forum and I really need your help!
"Create sum of multiple sheets and delete Duplicate Rows VBA MACRO FORMULA"
Hello. I am in desparate need of a formula or VBA or MACRO for my problem. I have a about 8 spreadsheets of 10,000+ entries. There are 10+ columns. Column A has account numbers and name, address follows next respectively and N has amount. There are many duplicates of different entries in many worksheets and I need to add up their amounts and make it into 1 row.
Thanks a lot in advance