The response is no longer valid: either is too old or has been used previously code example

Example: The response is no longer valid: either is too old or has been used previously

You will get timeout-or-duplicate problem if your captcha is validated twice. 
Save logs in a file in append mode and check if you are validating a Captcha 
twice.

# For Wordpress
remove if multiplr plugin has added captcha to the form. because at backend it 
is validating twice