Apollo Attempts to Match Imported Leads with Accounts in Its Database By Default, but You Can Disable This 

Leads in Salesforce cannot be associated with accounts (only contacts can), so we have to use their email domains to guess what accounts they might belong to (more on how this works here). Because of the imperfect nature of the guessing, however, there are occasionally leads which are matched to the incorrect accounts in Apollo.

To prevent this from happening, you can disable the matching algorithm altogether by going to Settings > Integrations > Salesforce > Contacts, and clicking the switch for Automatically match Salesforce Leads to Accounts in Apollo -