Firstname lastname and akismet spam filtering wanted on both

Hi,

I am using the prefered method for spam filtering on my forms https://contactform7.com/spam-filtering-with-akismet/

It is exactly what I need but I have two name fields: firstname and lastname. It works if I put it on 1 of these fields, but not if I use it on both. Is there a way to make it work?

Thanks

https://wecaredaycare.nl/inschrijven-2/

https://www.ads-software.com/plugins/contact-form-7/