Bônus de armadura não, outros efeitos sim.
Os bônus de armadura para AC não se acumulam.
Conforme listado no glossário de termos comuns:
An armor bonus applies to armor class and is granted by armor or by a spell or magical effect that mimics armor. Armor bonuses stack with all other bonuses to armor class (even with natural armor bonuses) except other armor bonuses.
E conforme listado no equipamento:
Each type of armor grants an armor bonus to AC, while shields grant a shield bonus to AC. The armor bonus from a suit of armor doesn't stack with other effects or items that grant an armor bonus. Similarly, the shield bonus from a shield doesn't stack with other effects that grant a shield bonus.
Quanto aos outros bônus e efeitos dos dois itens, como são itens em slots diferentes (slot de armadura e peito, respectivamente) com bônus diferentes, eles devem ser empilhados bem, já que, ao contrário de Bracers of Armor , Túnica de Pele de Cobra não tem uma cláusula que desativa suas outras habilidades quando outro bônus de armadura tem precedência.
Many magic items need to be donned by a character who wants to employ them or benefit from their abilities. It’s possible for a creature with a humanoid-shaped body to wear as many as 15 magic items at the same time. However, each of those items must be worn on (or over) a particular part of the body, known as a “slot.”
A humanoid-shaped body can be decked out in magic gear consisting of one item from each of the following groups, keyed to which slot on the body the item is worn.
[...]
Of course, a character may carry or possess as many items of the same type as he wishes. However, additional items beyond those in the slots listed above have no effect.