Normally, you should have sparks on all four, not two. Another words, if you crank or idle continuously and if the spark didn't end up in the spark plugs it could well easy end up in the igniter, destroying it.

First, you must confirm that you have supply voltage at the coil and igniter. A simple test light or DMM will do. Do you have power? If Yes go to second step.

Seconds, connect one end of the test light to + (positive) battery post, the other end to the - (negative) input on the coil. Do you see a flashing light when you crank? If not, replace the igniter.