Compare Field data of 2 different application form fields

Compare Field data of 2 different application form fields

I have 2 applications. 

1. daily records (contains form name as ORDERS)
2. monthly records (contains form name as ORDERS)

Both forms contains email field, such as

1. daily records(app)->orders(form)->Email(filed)
2. monthly records(app)->orders(form)->Email(filed)

now i want to compare those two emails, e.g.

if(form1 email == form2 email){
      cancel submit;
}

No any idea, how can i achieve this?