can i prevent the same data from being entered into multiple email fields

We ask for up to 4 email addresses but some respondents are entering the same data in all 4 fields.  Can we prvent that?

You could create conditions to check if your email fields are equal to each other and show a message and/or hide the submit button if they match:

https://www.jotform.com/help/316-How-to-Show-or-Hide-Fields-Base-on-User-s-Answer

Create sets of conditions to compare each field to the other.