As far as I am aware only one device can be used for DHCP on a network. DHCP hands out the ip addresses to devices as they connect. Servers really should have a static ip address. They need to have different ip addresses so they can identified correctly. As you say having 2 servers improves fault tolerance and depending on exactly how they are configured could speed up delivery of data.
Dell XPS 13 9370 (2018) review