Yes, you can incorporate both silicone conditioners and serums into your hair routine but it's not necessary and will depend on what kind of silicone is in each product. If your conditioner contains a large quantity of resilient silicone, it won't add much benefits to add a friendly silicone on top of it. But if for example your conditioner contains only a little bit of a light-friendly silicone but you want more protection, then it makes sense to add a resilient silicone serum on top of it. Make sure you always follow the proper washing routine to prevent build up and you'll get great results from your experiments!