Disappearing text in fields…

My web developer set up my Contact form using Contact Form 7, and I’ve been sending myself “test” enquiries to check that all is working fine. However, I’ve noticed something-if I send more than 1 enquiry from the same email address (I type an email address in the email field) and then send a second enquiry using that same email address within a few minutes….the text that I type in the Name, email address and phone fields starts to disappear as I type in the message field. I am assuming it has been set up so that 2 or more enquiries cannot be sent from the same email address?

Is this to prevent SPAM?

If this isn’t the case then I wonder if there is a glitch or another reason the fields above “Message” disappear when I type inside the Message field. Thanks for any help you can provide!