Based on the classical earthly-branch relations of your two zodiac animals — this combination may emphasize these tendencies; real people add the nuance.
Two of a kind — the mirror pairing
Dragon with Dragon is a self-punishing branch: two of the same temperament, each carrying the trait that tradition warns about when doubled — stubbornness, pride, or restlessness. The comfort of being understood is real, and so is the risk of amplifying each other's blind spots.
The fix is an outside counterweight: a mentor, a hobby, a third voice that breaks the echo.