If the account that you want to “merge” is listed multiple times but the account names are spelled the same, then you would reassign the account to the specific AE that is to have the account.
Once you reassign the account to one specific AE, then all of the other instances of the account will be removed. All of the billing history and data that was on the accounts will now be combined and shown on one line for the AE that has the account assigned to them.
To learn how to reassign an account, please see Account List - Reassign Accounts (Manager Access)
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