Using String patterns like {{=[:First Name:]}}, {{=[:LastName:]}}, {{=[:SSN:]}}, {{=[:Street Address:]}},.. will create the same values if the string pattern is used multiple times.
One workaround is to use {{=%beanshell% com.ca.sv.devtest.util.GenerateString.forRegex("[A-Za-z0-9]{5,15}");}} in VSI response. This option will create dynamic values based on the Regular expression.