I know they exist but I'm wondering if you had 2 devices plugged into the loom would they conflict?

I want to fit an OBD tracker but use a splitter, have the tracker tucked behind the dash and the remaining plug on the loom in the factory location.

There's 2 reason for this, Main one do you can't easily see if a tracker is fitted and also so I can diagnose faults without removing the tracker.

is your OBD tracker just drawing power from the OBD socket or is it actually interfacing with the OBD? 

I've not bought one yet but I assume it's more than powering via the OBD as I think it let's you know when engine is started.

Worth checking... some only use it for power