Your web developer is wrong. You do have multiple version of the homepage
You have the following:
http://wilkersoninsuranceagency.com/index.php
http://wilkersoninsuranceagency.com/
http://www.wilkersoninsuranceagency.com/index.php
http://www.wilkersoninsuranceagency.com/
I would first of all get your web developer to do a http:// to http://www. redirect across your whole site, so whenever any user lands on your site they atleast get put onto the same version.
As for with/without index.php you are getting these duplicates, I would ask the web developer to remove any references to index.php and just refer specifically to http://www.wilkersoninsuranceagency.com/ whilst also setting a canonical within the index.php to http://www.wilkersoninsuranceagency.com/
If your developer tries to fight this I would look for a new developer.
Just had a quick look through the site, your developer looks to be being lazy. https://gtmetrix.com/reports/wilkersoninsuranceagency.com/I6khUBrH under serve scaled images, they haven't bothered to resize it and that's making your website load slower.
http://wilkersoninsuranceagency.com/images/img0018.png is just a lazy way of naming images.