Inconsistent wideband comparison

Hey guys! I just recently updated my rb25det from the stock ecu to an emu black. I’ve got her idling and driving through the neighborhood so far. I’m getting ready to dial the VE table in and have been noticing a discrepancy between the wideband in the emu black and the AEM wideband controller in my gauge cluster. The value difference between the two controllers is roughly 1.5 on the a/f read out. The AEM controller I have used with the stock ecu for over 10 years and it always seemed accurate however now I’m questioning it. Both are 4.9 sensors and I have a feeling the voltage and ground source may be where my problem is. I did try swapping both sensors to controllers and got the exact same results, AEM controller reads 1.5 higher than the emu controller (ex. Emu reads 12 and AEM reads 13.5). I think I need to tie them both to the same voltage and ground supply however I’m unsure which is the most accurate. For the little driving and logging I’ve done, the external AEM seems to be more accurate for how the engine is responding with the a/f ratio but my little voice is saying the emu is the one I need to follow. Any insight on how to approach this issue? Thanks in advance!

Where are the sensors located in the exhaust? Could there be an air air-leak upstream of the AEM sensor that is not present with the EMU sensor?

One sensor is in the turbo elbow and the other is a few inches lower in the down pipe. Yesterday I used a smoke machine to look for leaks in the exhaust and found one downstream from both the sensors,nothing before them. I have since sealed the only leak I could find. When I swap sensors at the plug the controllers continue to read the same difference and do not swap lower and higher values. I think this means the issue is in the wiring?