Effects of double snubber for TRIAC on SSR?
The two circuits are for different purposes.
R17 and C18 are a snubber. They reduce spikes and quick changes in voltage (dv/dt) that can damage or misfire the triac.
R15 and C16 may be required for inductive loads. With an inductive load, for the first instant after the gate pulse, enough current may not flow through the triac to keep it ON. C16 stretches the gate pulse until current flows through the triac.
Edit: further explanation: R15 and C16 are not an effective snubber because the resistor value is too high. Also, R14 is connected to the middle. It might be possible to find values of R15 and C16 that could serve both purposes, but the cap value would be large and therefore expensive. So, you could omit 2 cheap parts but one part would be more expensive.