I have a FAST EZ EFI system with the obvious O2 used in my header. I want to install an Autometer DL data recorder tech that records rich/lean data with an O2 sensor. can i split the wiring one one sensor for both my ECM and the data recorder instead on having two O2 sensors? Thanks everyone.

Short answer
No, because the controller output voltage is converted by its internal circuitry into a variable current signal that can travel in one of two directions (positive or negative), depending on whether the mixture is rich or lean.

Joe

And don't forget with O2 sensors - rich can be lean and lean can be rich.

As the old saying goes "Rich men race lean and poor men race rich"