Deduplicate remaining duplicate spawners I could find
Utilities: cat npc/*/_mobs.txt | grep monster | sort | uniq -c | grep -v ' 1 '
cat maps/031-3.tmx | grep 'object id=' | cut -d' ' -f 5- | sort | uniq -c | grep -v ' 1'
NB: 016-1 has another overlapping MauvePlant spawner that has unconfigured delay (thus is not a direct duplicate). As changing it would change game mechanis, it is out of scope for this commit.
NB: One of the 031-1 Bat dupe was probably added in ff1acc14. I could not extract a reason, and did not look into who/what/why added the other duplicates.