Jolrael's Centaur

Shroud is a static ability. “Shroud” means “This permanent or player can’t be the target of spells or abilities.”

Multiple instances of shroud on the same permanent or player are redundant.

Flanking is a triggered ability that triggers during the declare blockers step. (See rule 509, “Declare Blockers Step.”) “Flanking” means “Whenever this creature becomes blocked by a creature without flanking, the blocking creature gets -1/-1 until end of turn.”

If a creature has multiple instances of flanking, each triggers separately.