Ok,
I spoke with our lead engineer, and he told me that in the original Para DI (with internal gain), the FX loop was not a True Insert path. The signal was split 50/50 from the normal path to the loop. So that is completely normal for that revision. All of the DI's made in the last 13 to 15 years have been modified for a True Insert path, as well as the addition of the external gain.

Unfortunately, we have a policy against distributing any schematics for our products new or old. So I wouldn't be able to get you a drawing of the circuit.