I too made some interesting discoveries a while back, when I had a closer look at this Renault ignition system. As already suggested, the reason for the difference in the waveform, between the the paired cylinders [1 & 4] - [2 & 3] is due to the way they are wired. Its a cheap way of achieving a "wasted spark" system.
This really is unforgivable, given that, we have all the hardware necessary to achieve sequential ignition. Sadly the ECU & circuitry has not been designed to take full advantage of the hardware! Weird isn't it?
With the circuit layout as it is, the coils are fired at the end of the exhaust stroke as well as the moment just before TDC (just prior to the compression stroke). Mind you, when you think about it, should we worry? So long as we understand the system then I am happy to deal with the fallout!
The circuit layout is as follows... The two coils closest to the gearbox are the only ones that receive a direct feed & the two coils closest to the timing belt are the only ones that are grounded directly. I have not refereed to cylinder numbers, because the French method just adds to the confusion.
Here is a crude diagram describing the wiring layout....
Here is a capture I made that tells the same tale as yours.....
Notice also the lower firing voltage in the coil that doesn't receive a full ground during the charging or dwell period. As Tom points out, the "Primary kick" does not have the same significance of the "Peak KV" that can be seen in secondary ignition analysis.