No, not all SS springs have 7 leafs. Current SS springs are based on the '68 SS Hemi A-body springs. These are early springs. The SS springs that I have are old '65 parts that came on the car. I've owned this car for a little over ten years, so I have no idea why they chose to use two rights. I can only assume it is as SGBarracuda has already said...they wanted to even out the stance. Most likely because this wasn't a race Hemi car, and it launched fine with the two rights.
Don't worry about a hijack...these guys have already pointed me in the right direction.