We have had pull request left and right for changing the behaviour of matching hosts for equality, including or excluding ports, usernames, and other properties, it seems unfortunatley there's no happy medium.
The canonical solution is to use a project local `./.ssh/config` to write two host configs (SSHKit, and thus Capistrano will pick that file up and apply it over anything it finds in your `~/.ssh/config`, and write two hosts example_service_server_one example_service_server_two, and refer to those in Capistrano, and add their properties in the project local ssh config.
Give it a try (it's documented in SSHKit, and Capistrano I believe) and let me know how you get on.