How to check if filename is already in target directory?

Is there a "rule condition" which checks if the filename under consideration exists in a specified directory?
For example:
If I want to create a directory of file aliases for flagged important files, how do I prevent duplicate target aliases when the rule is re-run.
Is there some way to detect if a the filename (or alias) is already present in the target folder before creating the alias?
Is there some applescript/automator trick perhaps?
Any assistance would be appreciated...
For example:
If I want to create a directory of file aliases for flagged important files, how do I prevent duplicate target aliases when the rule is re-run.
Is there some way to detect if a the filename (or alias) is already present in the target folder before creating the alias?
Is there some applescript/automator trick perhaps?
Any assistance would be appreciated...