The Equal Value Validator allows you to enforce validation on 2 fields. The value of the two fields must match before one may submit the form. For example, in the following form, we would like to validate "Verification Key" and "Confirm Verification Key" fields to be of equal value.
Figure 1: Adding Equal Value Validator into form
ID: verificationKey
Label: Verification Key
ID: confirmVerificationKey
Label: Confirm Verification Key
In "confirmVerificationKey" field, open up its properties and set the validator to "Equal Value Validator" in the "Choose Validator" tab. Then, go to the "Configure Equal Value Validator" tab as shown in the figure below.
Figure 2: Configuring Equal Value Validator
Make sure that the "Field Id" is pointing to the other field that requires validation, which in this case, to "verifictionKey". You may customize the Error Message to be shown when the validation fails.