Make the pops: Add the dark and semi-sweet chocolate and coconut oil to medium microwave-safe bowl. Microwave in 30-second increments, stirring between, until melted and smooth.
Whisk in the tahini and coconut milk. Carefully pour the mixture into popsicle molds and freeze for at least 4 hours, until solid.
Make the tahini caramel: In a small saucepan, whisk together the maple syrup and tahini. Cook over medium-low heat, stirring occasionally, until bubbling and slightly thickened, about 10 minutes. Pour into a heatproof liquid measuring cup and let cool (the caramel will continue to thicken.
Remove the chocolate tahini pops from the molds and place on a baking sheet lined with parchment paper. Pouring from the measuring cup, drizzle the tahini caramel quickly back and forth over the pops. Sprinkle the sesame seeds over the drizzle. Any leftover caramel can be stored in an airtight container in the refrigerator for up to 1 week.
Serve the pops immediately, or return to the freezer for a few minutes for the drizzle to harden. Store the pops in the freezer, covered, for up to 1 month.