found on curse mod, which have same name and modid as your
i created issue on his issue tracker already
https://minecraft.curseforge.com/projects/gravestone-mod/issues/41

Hello. Thank you for reporting.
Unfortunately I'm not planning to change mod ID in the nearest time - it'll break compatibility for all players which already using this mod. Or at least I'll not do it till next major Minecraft update.
Furthermore my mod was created much more earlier than other mod, you are pointed, so it is not my fault.