Something is definitely keeping that coil hot. I'd start looking at the cam or crank position sensor.
Taken from the OE service manual;
The 3 coils dual-fire the spark plugs on cylinders
1-6, 2-5 and/or 3-4. When one cylinder is being fired
(on compression stroke), the spark to the opposite
cylinder is being wasted (on exhaust stroke).
Battery voltage is supplied to the three ignition
coils from the ASD relay. The Powertrain Control
Module (PCM) opens and closes the ignition coil
ground circuit for ignition coil operation.
The coil is a 1 piece unit consisting of 3 different coils
Power is controlled by the PCM. Trace the wire harness from the coil back to the PCM and look for rub through or pinches that may have shorted one of the PCM ground signal lines to ground.
The shop that installed your coil should be able to hook up to the OBDII port and watch the cam/crank signal to make sure it is OK. They should also be able to check to see if one of the signal lines is staying grounded depending on engine position by Ohming out the signal lines.