I can only assume that the chip was worn when the spatter occured. duh!
As I mentioned before, when found, blood was spattered on most if not all of the chips.

If the chip was made in mid 1800's and was in continuous use in a popular saloon or gambling joint, I could easily see that the chips were in a worn condition by the late 1800s. Now the blood spatter might mark the last day that the chips saw the light of day for the last 100+ years. Maybe a police raid gone sour? Early in the 20th century there are reports of many police raid on private clubs in NY that most definitely used ivory (see article in last club mag)

I do agree that it appears that the chip does not have any wear on it post blood stain.

In any event, I think something nasty occured at the poker table.