A final dispositor can't occur if you have more than one domiciled planet in the chart. What makes a dispositor final is that every other planet leads back to it. Since Mars rules Aries, it is its own dispositor and does not go through the rulership chain to Capricorn, same for Mercury.
An example of a chart with a final dispositor would be: Sun in Aries, Moon in Cancer, Mercury in Taurus, Venus in Aries, Mars in Cancer, Jupiter in Libra, Saturn in Libra, Uranus in Gemini, Neptune in Leo, Pluto in Leo.
No matter which planet you start with everything leads back to the Cancer Moon.
Pluto - > Sun -> Mars -> Moon
Neptune -> Sun -> Mars -> Moon
Saturn -> Venus -> Mars ->Moon
Jupiter -> Venus -> Mars -> Moon
Venus -> Mars -> Moon
Mars -> Moon
Mercury -> Venus -> Mars -> Moon
etc