Generally, there is no advantage to using multiple databases or multiple servers.
Best practice is to point all instances of LinkFixer Advanced to the same Microsoft SQL Server database. This allows all instances of LinkFixer Advanced to know about the files and links that have been processed by all other instances.
The only exception to this rule would be the scenario where you are processing files that are located in different geographic locations. In order to avoid the Internet latency associated with trying to process files in one data center using and instance of LinkFixer Advanced that is located in a different data center, you could install an instance of LinkFixer Advanced and an instance of SQL Server in each data center in which you will be processing files. This will allow each instance of LinkFixer Advanced to operate at top speed because that instance is located in the same data center with both the data it is processing and the SQL server in which it is storing the data.