If al-Tirmidhi’s label hasan sahih concerns two known routes, which explanation is appropriate?

Hasan li-Dhatihi, Sahih li-Ghayrihi, and al-Tirmidhi’s Composite Terms

• Both grades necessarily apply to the same lone chain in exactly the same respect
• One route may be hasan and the other sahih
• Hasan here only means singularity, while sahih only means route count
• This formulation makes the two chains necessarily equal in grade