Is it possible to merge accounts with different names which are different enough to not show up in the 50 record limit search results when searching for the accounts?
In order to merge accounts, the wanted accounts need to show up in the same search result in order to select the needed accounts, and it is often impossible to get accounts with different names to show up in the same search result. Selecting one account, then searching for another resets the selection.
In order to merge accounts with different names, their names will need to be updated so they are close enough to be displayed in the search results.
This only relates to Salesforce Classic, in Lightning experience, it is possible to merge accounts with different names. Lightning account merges are only for non-Veeva accounts.
CRM Help Documentation: Account Merge Administration