There are lots of ways that probably all won't work.
left(Customer,4) will return 'Sony'. But this always picks the first 4 characters
If(left(Customer,4)='Sony','Sony',Customer) will only change Customers that start with Sony to 'Sony'. But it will leave other (duplicate) Customers alone.
subfield(Customer,' ',1) as Customer will return the string before the first space. If you have Customers with a space in their regular name this won't work.
left(Customer,index(Customer,' ',-1)-1) wil return everything before the last space.
If all that doesn't work you can try using wildcard mapping. But for that you have to identify the duplicates anyway.
Maybe you need to buy a data cleansing tool. Such tools are created to do things like this.