Prevent SSIS from executing same file from WINSCP upload more than once in SQL Job

I have a request of how to write an Execute SQL task in SSIS.   More of a fail safe for when a vendor's file does not make it to our system.    This is causing the below issue.

I have a SQL job Step 1 that successfully uploads a CSV File from a WINSCP Windows task script to retrieve the latest CSV file from a SFTP site.   Then the SQL job Step 2 sends the file to the SSIS package for loading into SQL.   The problem occurs when the SFTP site does not receive a new file.  
Step 1 does not fail because it successfully retrieved the latest file, however, Step 2 using the package fails because the file that was pulled already exists from the previous pull.   I need a way to check in the SSIS package to see if the dynamically named CSV file exists before processing.    I am very green to writing variables and I have never used the Script task command.  Is there a way to do this check before my package kicks off the For each file task by using the Execute SQL task  ?    

As a side note, I do not have permissions to delete older files off of the SFTP site.    And, even though the SQL Job Step 2 says it failed, it still executes the CSV file so now I have duplicate records for the same day.

Please advise exact steps as I am a beginner.
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