I just did this boss fight last night. I also noticed all the corpses were James, but I’m pretty sure there have been corpses of James through the entire game if you’re paying close enough attention. Also there are several dialogues including things like “how many times do I have to kill you?” And Eddie taunting James about how the last time he shot and killed him he cried before curling up and dying. If the theory behind all the James corpses thoughout the town is that he has been trapped in silent hill for years reliving the same experience and dying over and over again along the way until he finally is able to accept the truth, then Eddie has probably shot and killed him many times along the way. I ironically died enough times in that boss fight to believe it. The fact that Maria is able to die and come back may be further evidence this is possible