could be the opposite. Oswald as the patsy, and someone with a weapon w/ silencer fired when he heard the Oswald shots, to make sure the job was done.
Nobody would know if they were simultaneous, especially if there was a silencer in use. The entire case hinges upon acoustics, which are irrelevant in the echo chamber of Dealy Plaza, and also irrelevant if a silencer was in use.
The number of shots heard is not important. It's the number of wounds caused by bullets, and there were more than two. Oswald could not have shot 3 times in 5.6 seconds and hit anything except maybe on the first shot. What people saw, what the doctors saw far outweighs sounds.
It is as if the commission made a hypothesis and set out to prove it, rather than letting uncomfortable facts speak for themselves. A pretty silly and fouled up investigation. > 50% of the evidence suggests multiple shooters. Forget how many shots were "heard."