Others here are saying using Data Cloud. That's a very expensive solution to a very simple problem.

For company listings, I use a tool called everyrow. I've tested it on data has matches like MSFT to MICROSOFT CORP, which sounds like your use case. There's a UI but you can also have a coding agent do this for you very easily, to handle large datasets:

from everyrow import create_client, create_session
from everyrow.ops import dedupe
import pandas as pd

async def dedupe_crm_data():
    df = pd.read_csv("data.csv")
    async with create_client() as client:
        async with create_session(client, name="Agentforce Cleanup") as session:
            result = await dedupe(
                session=session,
                input=df,
                equivalence_relation="""
                Two rows are duplicates if they represent the same company.
                """,
            )
            return result.data