You have 12 volts on both terminals because its is not being grounded by the ECU. The ECU may not be receiving a signal from the distributor module or the ECU has a problem, maybe grounding as mentioned, or is bad. If you disconnect the distributor 2 prong connector and tap the male connect on the harness side that goes to the ECU, that should trigger the ECU to fire the coil.

You are reading the "dead end" 12V on both terminals because there is no current flow. If no current flow through a resistor (coil) the voltage drop will be zero, thus the presence of 12V on each terminal.
Ron