Duplicate Hyperbolae (Repeated Signal) - when detecting pipe

[CHDenvironmental]

Hello,
I've recently considered a short discussion on repeated signal when detecting pipe. Clearly, metal pipes create an unmistakable "ringer" down the entire GPR cross-section. The question I raise here is related to pipes that are non-metallic and are water filled, which are also known to create multiple hyperbolae. Please consider the attached cross-sections. The target identified as "double unknown" could be either a 2-inch plastic waterline, or a larger diameter (4-6" PVC) sewerline. I have interpreted the stacked hyperbolae as two pipes; because two of the cross-sections show the center of the hyperbolae slightly off-set. Still I wonder if I have interpreted this wrong and really it is one larger diameter pipe containing some water. Any comments appreciated.
Best,
CHD