Impact of having a 'dedicated server' vs using Amazon CloudFront CDN on SEO

Search Engines are quite familiar with the nature of CDNs and how IP scopes are being reused across the network. From the perspective of what you described I'm not aware of any potential issues or penalties from SEO point of view.

In fact, in many cases CDNs affect the SEO rating positively provided they are configured correctly. That positive effect comes from the improved security, faster page loading due to image indexing and other optimizations. Don't worry about the indicator showing you multiple IPs.