How many logos can I include in a single jotform?

There's no limit on how many logos/images you want to add to your form. However, if you're specifically talking about the Header Field, then you can only add 1 image to it.

If you want to have 2 or more images, you may use the Text Field as an alternative to the Header Field. This field should allow you to use HTML/CSS so you'll have more options and flexibility in adding multiple logos/images.

Adding multiple Image Fields can also be an alternative.