Multiple values for a single Key

Terraform
1

Is it possible to assign multiple values to a single key in a variable map? I want to create an Azure vnet resource with multiple DNS entries. I can not seem to figure out a way to do this. Any help would be appreciated.

variable "vnet_default"{
  type = map(any)
  default = ({})
}

vnet_default = (
    {
        name                = "vnet-Default-Prod"
        role                = "Default Production VNet"
        location            = "EastUS2"
        address_space       = "172.16.0.0/16" 
        dns_servers         = "'172.16.0.4', '172.16.0.5'"  
    }
)