In My clio I has tweeters in the dash and mid woofers in the doors. I replaced just the door cones with some JBLs, I still have the standard tweeters.
To check in the dash remove the air vent to access the compartment behind the grill. Yes the TWEETER has four cables two inputs (from the headunit) and two out (to the door). The tweeter has the crossover (capacitor etc) built into the tweeter which is a bit annoying because if you were to upgrade to new component speakers the mid woofer has the crossover on it. It is very confusing
Check behind the grills in the doors and see if you have any flying leads that match the cables on the output of the tweeters. If there is no cables, you need to follow the cable leaving the tweeter and see where it goes (hopefully to the door junction box) good hunting.
The renault tweeters are fine but the midwoofers are crap you just need to replace these, whilst you are doing this replace the rear 10cm speakers aswell.
Have you got a different headunit?
Get back to me with an update, do you want to email you a circuit diragram?