Is it possible to attach an Eglu Go hutch (without run) directly to a double height Zippi run?

No, it is not possible to attach the Eglu Go hutch directly to the double-height Zippi run. You can use the Zippi Tunnel System to connect the Eglu Go run to the Zippi Run - https://www.omlet.co.uk/shop/rabbit_products/zippi_rabbit_tunnel_system_and_burrow_pipe/