i tried to Alt-attack and it actually a dicey situation
the result i have

(1) The cavalry charge, hit the unit, moving through, turn around, charge again, and finally melee (sometimes with swords, sometimes with spears)

(2) The cavalry charge, hit the unit, switch to swords then melee.

can anyone confirm?

actually i like the primary/secondary setting.
i just think if the 'overrun setting' we so love in STW and MTW is gone, they should make the 'double-charge' setting as fixed, while we can choose between primary and secondary.

For Melee Cav
Primary: charge with spear but do not melee
Secondary: charge with spear then melee with swords.