You mean put tint film on top of the existing one?

Can but both film will void warranty. The previous one will say, putting another tint on top void warranty. The second one will say, the tint film is suppose to be stick on glass 

I suggest you replace the old one with new one. 

true also... because still need to see how it performs in real life situation where we park under the sun for 30 mins to 1-2 hours
they did mention both are jpj compliance

but i can choose to go darker if i want to (at first i wanted 70% front, 30% all around)

so now im thinking 50% all around (safer)

front windshield as long as can still see, JPJ shouldnt kacau too much

since 50% all around can still see whole car interior

if put sunshades won't have problems with JPJ right?

save some money also if compare to install tint

you have to cabut sunshade when got jpj roadblock. because sunshade also non jpj compliant.
i done that before. in the end i also bosan because cabut pasang every times. put tint is better for me.
i already adjusting to 50% vlt, when guard want to see my face, i just roll down the windows la.
when at 10am or super bright noon, 50% vlt is actually visible from outside like using 65-70% vlt.