DHCP and reservered IP's

i have noticed that when i enable dhcp on my server that it assigns a reserved ip to those that that get a dhcp assigned ip. is this normal?

Your DHCP service assigns IP reserved for other MAC?

it reserves the ip addresses to the clients MAC’s , including phones, whose ip addresses are automatically assigned via dhcp. in other words if you have a dhcp assigned ip address it has reserved that ip to the MAC of your device. is this normal? is there a way to delete the reserved IP? or in the least edit it?