Is there a way to set an IPv6 DNS address like the ipv4 dns option... example: "IP > DHCP Server > Networks > Choose an Address > Set DNS Servers"?
Is there an IPv6 equivalent option? or it will be a feature?

I am asking because if i set SLAAC with DHCPv6 Server then my devices picks the IPv6 DNS from the IPv4 DNS... and this prevents the internal host names to be resolved.

If i disable ipv6 then the problem is gone...
So now i deleted IPv6 DNS entries from the DNS table in "IP > DNS"
It works, but i don't have IPv6 DNS anymore.

Thanks.

Yes. Hopefully we'll get something a little more admin-friendly in future. Although I'm not sure if it will help you with your problem, because even IPv4 DNS can resolve all records, IPv6 DNS doesn't add anything extra, unless you have some IPv6-only devices.