Check Part Of String Value

Using Classic ASP and I currently have an issue with a form getting spammed.

They are entering a first name as a legitimate value which is fine, however they are then using the firstname and another name for the surname.

For Example -

Firstname = John

Surname = John Smith

What I want to be able to do is check the surname variable to see if begins with or contains the firstname value and then perform and action such as a redirect.

Example -

if ((mysurname begins with / contains the first name )) then response.redirect "a website"

Thank you in advance.