AC copper lines; suction line carrying cool gas at around 40°F (thicker copper pipe) and liquid line (thinner) carrying warm or hot / up to 110°F liquefied gas should not be insulated together / within a single insulation sleeve.
Because of a temperature differential between the suction line and surrounding air, those thicker copper pipes are almost always covered with condensation. Proper insulation is required (vapor proof type recommended, minimum R4 or per manufacturer recommendation) and prevents condensation from forming (or at least minimizes the amount of condensation).
Therefore, placing hot and cold refrigerant line inside a single insulation sleeve is not a good idea. It will result in suction line condensation and lower efficiency of your air conditioning system.
Liquid refrigerant lines (thinner copper tubing) are not required to be insulated. However, if they travel through some areas where the surrounding air temperature is higher than 110°F (attic), insulation installation is recommended as well.
So, definitely separate both AC refrigerant lines, insulate thicker / suction line using vapor proof foam insulation, and depending on your installation configuration consider adding insulation to the liquid line if necessary.